Canton issues

Hi all, 

This is ongoing for the last year and I gave up. The sound system canton has stopped working. The centre dash speaker works, front tweeters (no mids), rear tweeters (no mids) and no subwoofer either. Now I'm wondering to fork our for a new amp? It's not cheap. £550. The MOS cable from amp to the multimedia in glovebox has been changed. No luck. Wiring all fine. I can only think of an amp issue. When you change Canton Optimisation quickly from "All" to "Driver or front" the bass kicks in for a millisecond and that's it. I'm pointing to a new amp. Any advice will he greatly appreciated. 

Tia

Regards