Not taking responsibility!

The last straw has finally broken the camel's back. After taking my car to VW Rivonia for an oil change service and asking to check a rattle has left my car in need of major repairs. 20km after the service i have needed to put 2 pints of oil in and top up coolant. When returning my car to the dealership I am given the lame excuse that the \oil leak"and cracked radiator are a result of the existing rattle which happens to be a loose timing chain. 5 days at the dealership saw me having to mediate between the dealership and extended warranty sold to me by VW with no urgency from VW. Finally after i get all the necessary approvals the work is done. As I am on the way to collect the car I am told that the car has failed a compression test and that they would need to charge me for an extra 8 hrs labour to investigate the problem. I am unwilling to pay for this as my car never came to the dealership with these issues and am convinced this was caused in their workshop. After speaking to the condescending and mildly arrogant service manager who managed spin as many stories as he could and ended by saying it is what it is"