Third party hit my vehicle

I was at a sheesha bar and staff notified customers a vehicle matching the description of mine was damaged. I rushed outside to see my vehicle rammed by a third party stolen vehicle and police at scene. My vehicle was a brand new car but i had bought it from a auction and got it repaired but i wasnt the best at filling away all reciept. I also serviced from Mercedes and really took pride in looking after it. The police advised me to contact my insurance company as i was screaming my head off about what had happened. Later that night i got around to telling aviva what had happed, gave my crime ref and they started from the start of claim giving me inccorrct advice. They explained to me first i was entitled to a standard courtesy car because i had no driver details. After thought the next day i rang back explaining i wasnt in the vehicle at time
Of accident so regardless its not my fault and the fact vehicle was stolen as i found out from
Police. They then changed their story to giving me a like for like vehicle. After agonising long stretch of me waitiing they decided to investigate mainly because i think of the value of the vehicle and the fact they wanted nay excuse not to pay me out. I coopearted as much as i could and at the time could not find reciepts due to my lack of organisation skills however they kept penalising me the fact i never had the vehicle repaired to a good standard, never had recipts at that specific, damage from the accident was inconsistent and that my emails provided were not mine and declined my claim. They also called my claim fraudulent indirectly by outlining their terms relating to cancellation if policy and if a claim is invalid or exagerated.I complained and explained addressing all the points however they maintained their stance due to
The high amount of pay out it would result in. I have proof of my vehicle as in perfect condition but upto their specifications it wasnt although mercedes never ever mentioned any major problems when servicing. Overall i would say PLEASE DO NOT TAKE OUT INSURANCE WITH AVIVA !!!!! They literally look for excuses not to pay out especially if its a new car and it will cost them fair amount. I would never ever take any policy out and will recommend to everyone not to take out any policy with aviva. I realised by my experience and further by researching amd found aviva is known for such scandals. If only i had researched before taking out insurance. Now i will be going to Financial Ombudsman Service. Please share my experience with all family and friends. I was gutted with my experience and heartbroken. They left me hopeless with no support and made me feel so vulnerable and it took me 6 months to mentally recover of the accident damage and their responses.