2004 Renault Scenic electrics

Usual Renault problem areas on electrics but all came together. windows, keycard lost code, dash panel has just been replaced (cost me £100 ), now have an assorted list of warnings and they want another £50 to put on the computer and tell me how much to rectify,, (it has only come of the computer 4 days ago)..Tyre pressure sensor fault is one of the messages but i have been told they are not on my car, still £50 to investigate the cause!!Tried to sell the car but can't as too many unpredictable faults and Renault don't want to know unless i stump up the cash. Check injection is now the latest addition to the revitalised dash that just wants to emit loads of information to get me back to the dealer with my debit card. I though that it is not unreasonable to expect a key, a dash and non wearing items to last the life of the vehicle. but all only carry the warranty of the car. Time for a Golf again...