Sim

I have worked for mtn years ago and I have a personla contract with them ,so I lost my sim card because my phone was ****** and this happened 3 weeks ago and I went to do a simswop and to be told I can't dona simswop because my number is still under staff profile of which I left 4 years ago ,so they need to first remove me there ,for me to get a simswop.Everyday has been excuses for now 3 weeks and I can't access my otps,no communication with family and no business because of this.Noone bothers to communicate regarding feedback, iam left in the dark.What kind of a service provider is this and at the end of the month they expect me to pay the contract of which iam not able to use because of my sim.Please advice what I can do as iam now lost.Legal way is my last option because this now harassment!!!!!