I don't think you have to put up with this. A sensor failing is one thing, because they are easily damaged by moisture, by polish and by parking bumps. (Other drivers can reverse into your car without you even knowing.) But the control unit should be fitted in a clean, dry place, and if that has failed after just two years it is plainly "not of satisfactory quality" and you should demand or even sue for free replacement by the dealer who fitted it. Use the fact that aftermarket systems are less than half the price you paid in your argument with the dealer, and in court if necessary. If you don't want to do that, then follow the advise of Just Answer UK Car and replace with an aftermarket system at less than half the price. Your consumer rights are here: www.honestjohn.co.uk/faq/consumer-rights