Royal Administration Services Royal Centennial No Help at All - Not worth the hassle! Hanover Massachusetts

I purchased Royal Administration's Centennial extended warranty for my used 2007 Kia Sorento and was told it covered everything bumper to bumper except typical things like oil changes and brake issues. My rear differential is completely messed up so I need it replaced and they refuse to cover the replacement because they claim I had to change the rear differential fluid at 67,500 miles which I was never told about and have never heard of. I explained to them that I bought this truck used not at a Kia dealer and I was never informed during any time even at oil changes that I had to change the differential fluid. They cannot make the judgement that it was my negligence that caused the differential to break because the seal broke and fluid leaked out and got dirty so even if I had changed it, there would be no way to determine if the fluid was full and ok. This loophole was not stated on the brochure I received for their warranty service either. Now I am stuck paying over $2000 for repairs and a rental car and all they are covering is $84. I pay this company $75 per month and am going to be cancelling if we can not come to a fair resolution. Any non-mechanic on the street would not know about changing rear differential fluid at 67,500 miles unless it is recommended to them and it was never told to me. They are not even willing to split the cost with me.