Frustrated. Want my money back

Good day. I have been trying to downgrade my contact to prepaid for five months now and your staff keep submitting the paperwork and then for five months I keep getting billed I don't want to do business with MTN anymore . I don't know why the average person must be put through all this trouble because you guys do not train your staff properly and there is no customer care. I went to stoneridge mall five months ago for MTN to do the paperwork to downgrade my package to prepaid and nothing. Then the second time I went to greenstone mall MTN telling them what happened and they said they would do it again and nothing again. Then the third time I went back to greenstone mall MTN to complain and ask for my money back and for them to check and they said they had done what I asked I would not get my money back. I have had nothing but problems with MTN when I signed my contract with you guys your staff did not load my data package and it took your staff three months to sort it out and I had bills for not having data loaded. When MTN went on strike for three months I could not top up my data becaus MTN never got back to me. I would like this matter resolved and get my money back asap.