Opening *****ulent account and bad attitude from call center agents

I once got from a lady from MTN who was asking why I was not paying for MTN contract. I told her I don't have an MTN contract let alone an MTN number. To my surprise last month on my credit report there was MTN which is now in areas. I tried calling for this to be taken down but one is always confronted with rude call center agent who doesn't even capture the information and or record as they always say. Please urgently help as going through your call center does not help. This is a *****ulent activity as it was even opened when I was not working.