Where is your customer service?

My cell contract was migrated from Altech to MTN SP. Since I am due for an upgrade I contacted MTN Business to get the process started. I have spoken to 4 consultants requesting upgrade documents and a list of which devices are available for my upgrade and each time I was promised that it would be e-mailed to me, but I still have not received the information. Today I spent 2 hours on the phone with various people at MTN but I still have not received the info. It seems to be impossible to renew you contract with MTN. Unfortunately I have accumulated a credit over the years on my airtime and it would be foolish to cancel my contract. All I am asking is to do an upgrade