Can't Select Gears (Manual Trans.) - A4, B7, 2.0TFSI

while driving on fast on the road shifted up from gear no:3 to no:4 when i felt that my gear is not engaging on no:4. Stop the car, suddenly from gear no.1 to 6 no gear can be selected.

however, when the car is off gears go in smootly and without using a clutch pedal. now that's scary.

Audi wants me to bring the car in for a check and in case the problem is the clutch they quoted me R7'700.00 for clutch kit.

Please advise!!! :-(