Contaminated Fuel (Diesel 50ppm)

I filled up my car with what should have been Diesel 50ppm on 5 August 2021 at Engen Erasmusrand in Pretoria - the fuel was completely contaminated (we sampled it and it was BLACK). My car has now had to go in for repairs through no fault of my own and now I'm not only without car for the next while but also stuck with a bill for their fault. This is UNACCEPTABLE as there should be quality checks in place to ensure that this doesn't happen.

I'm not even sure what to do here - has this ever happened to anyone else??