Intermittent trailer brake warning on dash?

Hello, I just had the vehicle at the GM dealership. They said their analysis was a blown fuse. Their notes indicated a scan to find CB111B for trailer control module system low voltage. Their notes indicated they testing wiring for any shorts or high resistance and found no concerns.

This was done on Monday October 2nd.

Today I left for a long trip and got about an hour out on the drive and now I was faced with

One message - Service Suspension System

followed by several warnings of : Service Airbag

Needless to say, I have never seen these two messages before since owning this vehicle for the past two years. Didn't feel safe continuing on with my 10-hour trip with the air bag issue. Not sure if that means its disabled or not so I turn around and dropped it back off at the GM dealership.

Not that this would have anything to do with it. But I did jerry rig two horns into the top horn wiring as this vehicle's horns are weak. I would surely hope that wouldn't cause these two issues. Other than that, I have not done any work myself on the vehicle.

I am not sure of your occupation but for me something stinks with this latest event.

I had a scheduled service for oil change, tire rotation and looking into the trailer brake message for Monday October 1st. Additionally, mentioned to the service manager I wanted them to go through the vehicle and let me know if there are any other issues that need attention as I was planning several trips in October and wanted to be preemptive as best so to avoid a trip interruption.

As mentioned above they completed that work and returned the vehicle back to me on Monday October 1st.

I didn't drive the vehicle until today - October 3rd.

I find it very odd or there must have been some "hidden/cosmic force" on the vehicle to net the two issues today related to the suspension and air bag.

I just got the vehicle back and I have another bill from the dealership for $202

They said the airbag cause was B001A drivers' belt pretensioner deployment loop high resistance. Live data shows 3.8 ohms wiggled seat belt anchor and it jumps to 11.8 ohms. Z999 driver's seat belt connector repair.

Related to the suspension service warning:
Cause C0585, left rear shock absorber actuator circuit, C0590 right rear shock absorber actuator circuit. Both DTCs are stored in history.
Z999 no problem found on suspension

Reprogramed the suspension control module to the latest software level. Checked both rear shocks, ok.

Now here is the sweet sauce. Service manager said after all of that that the front brakes are down to 2mm and need to be replaced. However, on the inspection page from the October 1st service nothing was noted for the brakes --- the multi-inspection sheet shows front and rear listed as 7mm or greater (OK).

I had an appointment scheduled for Monday October 9th to replace the wheels as they have seen better days so now not only will the wheels be replaced but now I get new brakes too.

Sorry for the rant but. There is a trend and sad to say I do not have any other dealership options, not that would be any better.