Account query 3 months now

Long story short. I went to MTN to ask for early settlement because I wanted to stop my contract. They gave me the settlement amount and I paid it. IN FULL. Anyway Month end comes along & MTN takes my debit order. In the meantime I have immigrated to New Zealand and escalated my query to MTN head office and spoke to a Billie Jean, which in returned emailed me one or two emails. Last email from Billie claims that I have a R 4000.00 credit that needs to be paid out to me. I have the proof in my email. 3 months has gone by no payment \credit received"and my query is still not handled. My fiance went through to MTN head office and actually spoke to Billie herself about the account"