Gallaghertrish

I bought my CKL convertible last July... although it had the bluetooth and ipod integration roughed in - the dealer still wanted $1500 to have them both 'work' - crazy! So i started looking for an after market unit. Won't bore you with all the details but I bought one from Ebay that was suppose to work with my car... took it to an installer today and since I have Harmon Karmon, fiberoptic ... we were going to have to run cables back to the amp - I was okay with that... but when he got in there - the cable included will not attach to my amp. However, with the unit connected - all the steering wheel controls functioned - just no sound. He is saying he looked around and there is nothing he can do. But I can't give up.. just does not seem right that I have a unit that fits perfectly in where my command unit is... there has to be a way to put in an after market on a CLK with Harmon Karmon, Fiber optic - isn't there? I want to have this done professionally but I guess I need to know that it can be done... without rewiring the whole car! Can it be done? How?
Thanks