Why are Mtn agents selling registered SIM cards

I bought an mtn SIM card around 2016/17, but recently I accidentally locked the SIM card. I went to the nearest mtn office around, so I gave them some info about the line, so I can get my PUK, and they told me my name is correct but the picture, and some other details are wrong. Please what can I do? cuz they told me that the line is gone. My bank accounts are connected to the line also my NIN. I’ve used this number for so many things. Pls I can’t lose it. Thank you