CD changer compatibilitty

[Beachie]

Hi.

I have a 2006 A6 C6 with CD changer in the glovebox, model number 4E0 035 110A. CDs load into this but don't play and don't eject. I bought the car with this problem. I have looked all over the place for the same model number but the ones that come up are horrifically priced. Are there other model numbers that are compatible that I can use? A popular one that comes up for sale ends in 111, rather than 110. 

What are the differences between various models?

Thanks in advance.