How long should a gear box and clutch on an Audi A4 last?

I have a 2003, A4 6 speed manual, I bought the car new. The car has been in for repairs once a month for the last six months. The last time I went to pick up the car the clutch (all of a sudden) started fighting me to go into gear especially 1st and reverse, I complained and the shop (car dealer) told me that I have to replace the clutch and Gear Box, I have 88,000 miles on the car. The dealer told me the cost of the gear box is $5300.00 and the clutch and additional $1,200 to $1,500. HELP!!! I haven't #!1qaj~# even fished paying for the car, and they want me to spend $7,000 without New York taxes (which by the way are 8.375%). The shops philosophy is to replace not fix and I don't believe they know what the #!1qaj~# their doing anyway. Any ideas, thoughts or suggestions would be thankful and appreciated.

FYI I took the car into service two moths ago because of a flashing check engine light, they replace a coil, one month later it started flashing again, this time they replaced two coils, ONE week later the check engine light came on again, this time its not flashing they tell me I need two catalytic converters changed each one cost $1,100, by the way this is the second time they were replaced.