Suscribed for 2gig recurring service

I have 3 contracts with MTN and today I decided to check my statement. I noticed that for 1 phone I have been overcharged. I decided to query this by calling MTN and the first person I spoke to said I have an additional service of additional 2gig of data. I told him that I have never subscribed for such and the last time I called MTN I was complaining about being overcharged airtime and data so why would I subscribe for an additional service with MTN while I am not impressed with the service. The guy asked me to hold on and then hung up on me. I called again and spoke to a guy Robin, I told him the same story and asked him to provide me with evidence of me subscribing for example a voice recording of my call requesting that service. He said he doesn't know how to obtain one and asked me to hold on while he enquired. He got back to me and said no one is able to assist and he will escalate the matter and send me a reference number. It has been 3 hours and I am still waiting for the reference number. Please assist as I feel like I am being taken for a ride by MTN.