A couple of years a ago there was some sort of fuel shortage in JNB. I operated a 788 freighter from London to Jo'burg tanking fuel and planned to land just below MLW. We filled it up out of LHR. We requested 03L in JNB (4418m) as opposed to the nominated landing runway in use of 03R (3400m) as we needed the extra landing distance. ATC asked us 3 time why we could not accept 03R before begrudgingly allowing us to land on 03L.
We landed with enough fuel to turn around and make anywhere in West Africa.