The lender has 40 days in which to respond to a SARN. After that they are breaking the law and you can make complaint to the Information Commissioner. Has your cheque been cashed? If not, cancel it and send the SARN notice again, but send recorded delivery (assuming you didn't the first time) that way you can show that Halifax definitely got it.(posted 7973 days ago)Personally, I would wait until you get your SARN data before entering negotiations. This is because there may be some useful information in the paperwork you receive. Even if you don't have a strong enough legal argument to write off the entire shortfall, most people have found that there are spurious charges which make up that shortfall, and this is what you need to argue against.