Misquoted repair by R8000!

I am extremely disappointed at the service I received from Audi Rivonia on the 23rd of September. My car was in for a standard oil change service and I requested that they check my water coolant bottle as it seems to be leaking. Half way through my morning I received a text message saying that it will cost R1282.00 to repair over and above my R2420 service. ( I am just out of motor plan ). I said its fine and they can repair it. Upon going to collect my car expecting a bill of just under R4000 to my horror I had an invoice for R12832,71! The service agent who sent me the text message quoting the additional repair had left a zero off the figure. I would never have given the go ahead on the repair if I had know it was R12k! A lot more than what I was expecting to pay. I ended up getting them to take off the labour charge but still ended up paying R3000 more than what was 'quoted' to me. I feel that Audi should have paid for their mistake instead I was the one to take the hit.