Most terrible company ever

I closed an account and had a few rand outstanding. When I heard about that I contacted the company and paid it. I have tries SOOOO many times to tell MBD this. They ask me for proof, then I email it to them (which I've done probably 5 times already( but they still call me. Then when I explain to them that I have paid and that I have emailed proof, they just put the phone down. This is most terrible experience I've ever had. Will this EVER STOP???