I had them say that about a problem i had on a cavalier when the steering shaft was clunking but it was still working....
I had to ask them do i wait for it to break, loose control ect and then try to bring whats left of the car back in for service ... they ended up fixing it after that (under warrenty)
Anyways the car is still out but Ill be seeing if the tension has any play ....
Was your belt cracked or something ?