Warranty

I purchased an HP Pavilion 23 All-In-One, B231 model from Aaron's store in December 2013. Officially, my HP warranty expires on September 13, 2014. Since I purchased the product, I called HP support THREE TIMES and purchased extended warranty for three years including accidental damage. However, when I tried to activate the coverage, first online and then over the phone with the HP customer care representatives, I was told that the certificates "we're not compatible with this HP product." So, full,refund was issued three times. Over the next few months, I called and I emailed so many people at HP, and each time they were giving me the same extended coverage that another employees who work on warranty activation told me were incompatible. When I asked those warranty reps to tell which coverage is compatible, they couldn't tell me, since they don't sell it, they only activate it. Luck will have it that my PC screen went berserk so today I'm shipping it to HP for repairs, but I still need to buy extended warranty. What to do? Can someone point me in the right direction?

Thanks!