147 - Sat nav problems

The sat nav on my alfa is having problems.

It is working fine - until about 10 mins and then goes through a cycle of switching itself on/off/on/off and then stays off. Swithcing it back on and it does the same thing.

I took it into the dealer who said there was no loose connections and that they would could replace the head unit - costing £1400!!!! ...and yes the car is 10 months out of warranty.

I had a look on eBay - found a new unit - albeit for a Fiat - but everything looked the same apart from a different fasia.

I swapped the units and the fascia - hey presto....except now the sat nav map doesnt keep track of where I am, the start up screen is FIAT and the steering wheel controls are reversed. There is a 'set-up' CD but this doesnt do anything.

I want to sell this car but I dont know what to do next?I cant afford a new sat nav and I cant really afford to sell the car at a whopping discount.

Any ideas anyone?? Please??