I have often visited this particular service center, so I feel I am qualified to give you a feedback.
If you exactly know what is the problem and what you want to get done, then it's ok to visit this place. If you want them to diagnose your issue, I don't see any person there. Even if some mechanic comes to know your issue, he will just do what supervisor tells him to do, no more no less.
However, you can get an estimate from them & decide what you want to do.