Poor customer service

I have done an upgrade on my mobile phone with MTN on 18/04/2016. My previous contract was a data contract which I upgraded to a regular mobile phone. I requested to have one of my prepaid line to be migrated to contract with this upgrade. I was informed by the sales person that all was done. On 20/4/2016 I realized that my line was still prepaid and was not migrated. I called 808 and got Andrew on the line. After explaining my issue this agent referred me to the prepaid help desk. Having dealt with MTN for a number of years I knew that prepaid help desk was not equipped to deal with contract queries. I challenged Andrew on that and ended up requesting to speak with his manager. The agent told me he was not willing to let me talk to the manager because I had not explain what my query was. He actually told me to call back and speak to someone else if I was not happy. For a paying customer who has been loyal to MTN for many years this experience left a bitter taste and I would like to see this matter addressed.