I recently bought a car from a private seller. Before I bought the car I did a HPI check by text, which came back clear. When viewing I took a mechanic with me and, because the check came back clear, the mechanic and I tested the car and we agreed on buying the vehicle. Then, I found out a month or so later that the vehicle was a total loss category D write-off. I've contacted the HPI checking company that I think are at fault, who have asked me to supply to them loads of paperwork relating to the car. I find this odd. What would you suggest?