BAS/ESP light on

I would think with that description all it likely needs are new brake pads and the wear sensors replaced. The lower pedal is because the pads are worn and the lights are on because the wear sensor(s) are triggering that the pads are worn. They are nothing but a plastic piece with a small rod inside connected to the brake system, as the pads wear the plastic wears as well, When it wears to the point the rod is exposed it completes a circuit through the brake rotor telling you the brakes need to be serviced. The fact that it doesn't come on with a light pedal but does under heavier braking shows that there is some flex in the brakes (totally normal) and they are just starting to touch. That should mean a standard brake service with new pads and possibly rotors if they are worn but with 32K It would depend on how much it was actually driven as the rotors could be failing from rust and not just wear.
If you don't see any leakage or other issues with the booster or master cylinder then I wouldn't think they are a problem.
If the car sets around a lot it will likely just need the rotors and pads, probably all 4 corners as well if it's due to rusting as the rotors love to rust if a car sets.

I would also say you should find a better shop, those are not hard brakes to service and a dealer would be overkill really. Oh, if you didn't know, although that car says Chrysler on it, it is actually mostly a Mercedes SLK with a different set of body panels.

For brake replacement:

The fronts have the wear sensors so we will start there. Jack up the car and remove the front tires (or tire if you want to do them one side at a time. Secure the car on a stand, not the jack. With the tire off the brake caliper will be in front of you, It is retained by the metal clips, those pry off, Use a pry bar to force the caliper out and push the piston into the caliper. Now disconnect the wire in the top center of the pad for the wear sensor.

Next you need to remove the slide pin caps and then the caliper slide pins. Set those aside. The caliper will now slide up out of the mount. The pads can now be removed. With them out of the way clean up all of the points the pads touch on the calipers and mount with a wire brush, file or sandpaper.

If you are replacing the rotors as well you would now use a wrench to remove the bolts that secure the caliper mounting bracket to the steering knuckle, then remove the retaining screw from the rotor and remove the rotor. Clean the face of the hub of any dirt or rust and install the new rotor. Reinstall the retaining screw if you wish, it makes putting the caliper on a bit easier but isn't really needed.
Now reinstall the caliper mounting bracket, torque the bolts to 85 ft lbs.
Now lube the pads and caliper where they rub on the bracket and each other, use a silicone brake lube. Place the pads on, then the caliper. Install the new wear indicators into place and then take the slide pins and clean them, then apply some lube to those and install them, They are tightened to 18 ft lbs.
Reinstall the caps. Now use the new caliper anti rattle springs and install those the way the old ones were. Plug the wear sensors back in.
Put the tire back on, torque the lug nuts and set that side down. Repeat the process on the opposite side. Now for the important part, get in the car and don't start it, just step on the brakes a few times to push the caliper pistons out so the pads touch the rotors and you have a solid pedal. Now if you plan on doing the rears you can do that now or I would suggest taking it for a short test drive first. Go a few feet and test that you have brakes. Now go out and drive at about 30 mph and step on the brakes, repeat that about 5 times, then go up to 50 mph and do the same thing. You have now bedded the pads and verified they work.

Time to do the rears, These are a bit easier as you only need to remove the mounting bolts, then use the pry bar to compress both pistons. Now lift the caliper up and knock out the pad retaining pin that also releases the anti rattle clips. Remove the pads. Clean the rubbing surfaces and apply brake grease. Install the new pads and clips and then tap the pin back into place so it holds the pads and the clips. Then put the caliper over the rotor and reinstall the bolts, They are tightened to 41 ft lbs.
If you want to replace the rotors you do so when the calipers are off, remove the retaining screw, clean the hub, install the new rotor and screw. Then put the caliper back on.
Then do the same with the brake pedal, engine off. Then test them. Now if everything is working, go out and drive it with the same 30 then 50 mph stops. Then take it out where you can drive it for a while under stop and go. Drive a few miles and check each corner with your hand to see if anything is heating up excessively. If not, you're done. The light should stay off until the next time the car needs brakes.

For some more info and a guide on the parts you can look at these. Not the same vehicle but the process is very similar.

https://www.2carpros.com/articles/how-to-replace-front-brake-pads-and-rotors-fwd
https://www.2carpros.com/articles/how-to-replace-rear-brake-pads-and-rotors

Sounds like one of my local dealers, "Yeah that is a warranty part, but sorry nobody can get it" Sort of makes the "lifetime warranty" a bit useless. Mercedes is usually very good for parts availability, sadly they didn't seem to pass that on when they owned Chrysler. Now that Peugeot owns them it will be interesting to see if things get better or not.
I'm semi-retired myself, I sold my shop and was supposed to walk away and only work on friends and family stuff if I wanted to. Think I'm busier now than I was then.
With the same dealer acting that way, maybe try a different one if there are any not under the same roof, In my area that doesn't work so well as there are basically 3 families that own everything in a 100 mile radius.