Car on finance buy broke beyond repair

[Ree]

I have a car on finance buy it is broken beyond repair. I has gone in for its MOT but it needs a new engine. I has a service plan that ran along side the finance which has now been cancelled. Under the service plan the car was last serviced just short of 2 years ago. It hasn't had a service since and has done 27000 miles since. The mechanic who was doing the mot failed it because of high emissions. When he investigated he said the air filter and oil filters where in the worst condition he'd seen in his 40 years of being a mechanic and he believed neither filtered had been changed in over 5 years. He said these should have been changed during the cars services. The car now needs a new engine. I can't afford for a new engine and I have 12 months left on the finance. Would it be reasonable for me to go back to the service plan providers and ask them to explain why these filter were not changed and also what should I do about the finance company