defualt

I made payment in December and they stopped my medical aid I don't know why. After many fights and calls and sending the proof of payment to them they just kept quite. I got a letter from them that said I ow them 686.00 fore payment done by them toy Dr . after calling them and resending the payment I made in December of ower 4000 rand and got a ref number for it and herd nothing again from them and then there was a default put against my name. I want this sorted or I wil be forced to take legal steps.