Debited for a cancelled contract

MTN your call center agents dropped my call as they usually do, claiming they can't hear me. I would like your detailed explanation in writing as to why I was debited for a contract that I canceled within the stipulated 7 days of receiving the sim card. As per the conversations I had with your many call center personnel, I stated that there is no LTE connectivity in my area even though the website and your sales person confirmed that I had. Immediately after realizing that I couldn't connect, I called to cancel my contract, and the contract was cancelled the sim was converted to prepaid. Today I woke up to a debit from mtn, I reversed the debit and I hope to hear from you in writing. The number in question is: *** Cancellation reference is: RCO178580 I have never used your data, the sim was converted to prepaid while I was talking with your call center personnel on the phone.