Horrible service

I have been trying to upgrade my contract at MTN and I was told to pay my March installment date before my paydate in order for me to upgrade. So I paid it on the 24th March. I went to the store on the 25th and was told it's declining and still showing I am in arrears and they will follow up. On my the 28th I missed their call and called back to the Cavendish branch and I was placed on hold until my airtime finished. I tried and tried but the branch wasn't answering and only got a call back Thursday the 31st. To be told that the upgrade was onto a wrong number and that they will re-apply. I waited and got a Debi heck on Friday to approve. On Tuesday the 5th of April I was asked to collect ams there were complications with colours. I am in the store now and told that it declined again with the same reason of arrears whereas the March payment was done. When I ask the agent why she does not know. This kind of service is unacceptable