SIM Card ***** led to my identity theft

My MTN number this month has been **********ly been ported more than once to outside networks providers. That person or persons stole my identity to **********ly try to look as if I'm the one opening those credits. Without saying too much, the ***** Department takes me to a voicemail after ringing for awhile. I need to report this number to the ***** Department. Today it shows that the MTN number is back with MTN service provider however it's being recycled. This is serious as this person or people knew my bank details, and my ID number. I want answers ASAP from the ***** Department please.