BP garages with contaminated petrol

very dissapointed with the BP garage at Bernie Street, River Rd, Randburg, 2162, on the 9 April my wife stopped at the garage to get petrol and she was informed that they are out of 95 and she can use 93, they put it in the tank and on driving off the car switched of and till now has not switched on . On getting it to the dealership i am sitting with a bill of over R15000 because they put in contaminated petrol(had water) which has ****ed most of my engine components. and now i need to face this alone while the garage is at fault