Medihelp refuses to pay subsequent tests

Late last year I fell ill and went to the doctor who recommended that I test for covid which came back positive, I waited 14 days and went to test again and it still came back positive, I waited another 14 days but it still came back as positive, I only got a negative test on the 4th attempt, my employer said I will only be allowed back to work if I produced a negative test, to my surprise, medihelp has only paid for the first test and has refused to pay for the other three tests, I recently received a letter of demand for an amount of 2550 from lancet laborities, at the time I was not informed that they only cover a single test, my wife is due to give birth soon and we will only be allowed in hospital if we produce negative tests, otherwise I won't be allowed inside