Car damaged after service/ repairs

I booked in my car for service on 09/11/2015 monday for service tuesday10/11/2015 for oil service which was R1608.65 and i had the engine light come on from time to time when driving over 120km/h but the car was fine and drive-able, they did diagnostics for the engine light and said it was pressure converters and vacume pipes and quoted me R8282.66 to fix that and the total quote including the service and vat was R11276.09 which i paid and in possession of the proof of payment, i got a phone call to come collect my car as if was fixed and tested on wednesday 10/11/2015 in the afternoon, i was at work so i picked it up on thursday morning 11/11/2015 on my way to work and before i left the premises of auto bavaria midrand the engine light came on and the car had no power which is a worste state than what the car came in, they checked the car again and when they where testing it on the road as i was told it was driven for 30km they burst the boost pipe and now expect me to pay for it, they damaged my car further with their tests on the road, i want my car fixed as i have paiid for it immidiately.