I have a 2012 Lexus RX450h. Two years ago I had an advisory on the MoT that the rear nearside fuel pipes were corroded. I wire brushed them down and painted them with Hammerite. The next MoT I was advised that the pipes were corroded but covered in underseal. I have just had the car serviced by Lexus and asked them to quote to replace the pipes. They have stated that no work is necessary as it is only light surface rust. What should I do as I don't want advisories and don't want to be seen as not looking after the car? And I don't want to pay £500 without cause.