Migration from contract to prepaid

My contract expired on the 7th April and today it is the 13th April. I have been calling MTN to migrate my entire account and it has still not been done. I went to the Cresta branch on Saturday thinking they could help me but they said only the cancellation department can do it and they work Mon-Fri, they also mentioned that I will be billed for the contract because the migration has not happened yet. I called on the 808 number on the 7th April and the call kept on cutting. I called on the 8th and was given this reference number *** by Mapaseka. I called again on the 9th an was told it will get done. Now after after visiting the Cresta branch I was told to just wait . Now I just tried to call twice and i keep getting cut on the 808 line. Please can you get this done and make sure I don't get billed for this month simply because people in the cancellation department don't want to do their work. I am not impressed at all.