Victim of identity theft

Someone opened a ********** contract with MTN using my identity, I informed MtN 3 months ago.They advised me to submit a written affidavit to their nearest store.I was informed that the matter will be investigated and I will be given feedback within the next 21 days. Well it’s 3 months and today I get a call from MTN Debt collectors. MTN is useless and have weak security controls