 Its4Me car insurance- lost security certificate for car immobiliser
we recently set up car insurance with ITS4ME, part of swinton insurance. upon completion of our online application we were sent a letter asking for the original documentation regarding the immobiliser in the car. wwe stupidly didn't copy the documents before sending them, but as the car already had the device fitted when it was bought second had we werent sure if we had the exact document they had requested an so sent everything we had relating to the immobiliser including the serial number and the instruction manual. a coluple of weeks later we recieved a letter from the company claiming libility that they had lost all of our security documents. their advice was to visit a local registered garage and they would be able to replace the certificate. this proved not possible because it is a peugeot immobiliser fitted to a nissan car, therefore becoming untraceable. it was also said by the garage that should any problems arise with the immobiliser in the car they could not be rectified without the original documentation and the only option was to have the immobiliser replaced. this was our proposition to the insurance company as they had already claimed liability. however we then recieved a letter back saying that thy had reviewed the case and that there was no possible way the could repalce the immobiliser, and sent a letter to forward to future insurance companies, to say that the car does have an immobiliser fitted, but that they had lost it. this solves the problem temporarily, but does not enable us to rectify any future possible problems with the immobiliser, neither will this be satisfactory if in future we come to sell the car. they also stated in the letter that we should find enclosed £20 worth of vouchers for the trouble they had caused... which incidently weren't included in the letter. we do not feel that this is a satisfactory solution to the problem and feel that as they have claimed liability they should pay for the fitment of a new immobiliser, they claim that they have taken the case as far as they can within their company.
does anyone have any advice as to where we can go from here and whether we have a reasonable arguement? | 
