Can't get my car to shift into gears

I own a 2004 saturn ion 2.2l manual. I have trouble where I can't get my car to shift into gears. The gears become extremely difficult to go into, especially reverse. Even with my car off, I have trouble shifting into gears. Some times become so difficult that I feel I wont make it to my destination.

I've had my mechanic replace my clutch master cylinder and look at the shifter cable and everything was working fine for about 3 months and it became difficult to shift again. A year later it hasn't gotten any better.

I've had many issues with the transmission. The roll pin/cotter pin that goes inside the shifting linkage has broke/fallen out on 5 occasions which left my stranded. I had tried many fixes to keep the pin in, and the only one that has lasted as a last resort was a bolt was tac welded in.

My 3rd and 4th gears grind horribly. Especially a downshift into third, it is almost impossible. Im guessing thats just bad synchros.

I can deal with grinding and avoiding gears. But my question is what could be causing my car to not shift at all? Making me try numerous times before able to go into gear. Grinding when I try to put it in reverse.

Is this car just a lemon and should I move on? I've tried fixing the shifting many times now. And of recently too my clutch pedal pops out of place because the back of the pedal is plastic and the groove has been worn away from use. I asked a mechanic and they said I would need a whole new clutch assembly