damaged vehicle

I took my car for its routine 120 000 service intervals and i received my car the same day. i drove the car home and came back to work the following day. my car started misfiring and i call Audi centre as they serviced the car. They told me thatvthe timing had jumped andbthey had to replace the timing chain and the tensioner. i advised them that the car is covered by a warranty and they submitted their claim. my warranty (AMP) then advused them that they will only be paying for the tensioner and i was advised that i would need to pay for the shortfall. i was going to get my car in 2 days time. after 2 days i went to the centre to collect my car and was now told that one of the valves on cylinder had bent. my policy does not cover bent valves. Audi is saying this is as a result of the tensioner and they want me to pay for all the repairs which at this point are sitting at R24 000 plus. My car was driving well and the only mistake i made was to take it to Audi as a reputable service provide, instead of getting one of my RMI friends to fix it. I sit here without a car and debt of the shortfall. I was assured that the problem was the timing chain and once that is sorted i will have my car back. Audi refuses to take responsibility and i now have to fix the car on my own with an RMI certified dealer as Audi inflates their prices and charge for the same thing more than twice.