Innovation insurance and Ford's failure to support their claims and warranty

I purchased a Ford wild track in October 2015 with 21000km on the clock. During my purchase I bought an additional mechanical failure policy form Innovation. Returning from a dream holiday of doing the dunes in Namibia the engine blew, because of over fueling of the 2nd fuel injector, burning a whole in the piston. This is at 71000km, an mileage when a motor is normally still considered new. Is this mechanical failure of the engine and actually failure of the manufacturing. I believe it is. However I had insurance, or so I thought, Innovation refused to pay, and ford ignored all communication. I landed up having to buy a new engine, cash. Now this new engine is giving me trouble, and ford are wanting to charge me again for parts and labor although it all is supposed to be under warranty. This vehicle has been a very expensive bad decision.