Contract cancelation!

I gave cell c a month notice to cancel my contract end of May 2018 Last week I call their retentions department to confirm that my contract will expire end of May and my number converted to prepaid. The consultant asks me why I don't want to upgrade. I tell him, I didnt get a great deal with Cell C. He asks me what phone I am looking for and I tell him. He promises to contact sales and get a great deal for me, at my budget. I even email him MTN specials and he promises to check if cell c can't beat the deal otherwise he will convert my number to prepaid by end of May. Today I follow up, and he simply tells me cell c cant beat the deal. I then ask via email that he proceed with cancellation and process my number as prepaid. He then tell me "You will have to phone in and ask for cancellation, you called and asked for me to assist you with deal match, Call 084 143 option 2" WTH! Why is cell c giving me a hard time to just cancel my contract???