Innovation group waranty

I took an aftermarket waranty with innovation group through mfc almost 3 years ago.i claimed plus minus a year later and I had no issues.they payed the claim with the help of my gap cover.the car was purchased with an aftermarket exhaust system and that is the only "modification " I am aware of.a month and a half ago I had issues with my car so I took it to an rmi workshop.the mechanic said it was head gasket failure.i had him put a claim through to innovation.then the run around started.i was 1st told that the go ahead to strip and access was given.approximately 3 weeks later after multiple calls(minimum waiting time 45mins per call)I was told that the workshop is not on innovations list of workshops and I will need to take my car to one of their listed workshops.after much protesting I was told that the matter will be taken to higher authority.i then received a call a few days later stating that I will have to sign a disclaimer form.the form was sent to me and I filled all the details required. Then the run around started once more.i was then told that an assessor will be going to check the car.a few days later the mechanic confirmed that an assessor came to the workshop.after a few more calls I was told thay the workshop will get a once of dealer code.once the code was given and the workshop ran the process of the claim he was told that they could not update their labour rates and the only person that could do it was in a meeting.he was told to call back in an hour.i then recieved an email a few days later stating that my claim was rejected due to the car being modified. No details was given as to what modifications they were referring to.i sent emails requesting details and also a copy of my recording when my policy was taken and to date I have not gotten a single response.