MTN Telemarketers - Be very cautious

I agreed to upgrade my contract with one of MTN's telemarketing partners and have had nothing but the run around ever since. They told me that I could switch my account to my business once I had done the upgrade which is apparently impossible. I have never received an invoice or a copy of the contract or any paperwork whatsoever. They have simply disappeared into thin air. Be very wary of dealing with these "telemarketers".