Interesting transmission issue

[PimpDaddyJ]

Just looking for advice on this one, took my car in to get 3rd gear syncro checked, they replaced it and the gear under warrenty, Next day and 250 km later when i goto visit my mom, on the highway 5th gear shoots back into neutral, 4th gear wont go, i coast in nutral for a little bit, and it goes back into 4th, i get to my moms a few minutes later, 1st gear crunches like crazy and so does second, i then park the car. I then notice theres dripping under the car, get it towed to the dealership at that point. The dealership tells me that somehow my drain plug fell out(missing detent ball/spring) so they top up the fluid and say nothing is wrong with my transmission, and that its my clutch release bearing thats sticking, and that my mazdaspeed clutch is worn out anyway so i should buy a new one and that the grinding that never happend before is co-incedental...The current clutch i have in there is not a mazdaspeed clutch and has 12,000 km on it now. Now I can understand that since its not a stock clutch and if its causing a problem shifting i will get a new one, it just strikes me odd that this problem is occuring after my drain plug was improperly installed by them. Occasionally it will pop out of first now and/or get stuck when i try and shift out of first, but no other gears. It also sounds like an empty metal drum when you put it in first and tap ontop of the shifter (is that normal!??!) Just some insight into what the problem may be, if i have to pay to get it fixed i'll pay, if its something i shouldnt be paying for since the car is still under warrenty i dont want to get hosed.

Thanks