Alledged Spam call from MTN????

A lady just called me from this number ***, claiming that a client currently wants to do a simswop on my number and shes forwarding an OTP number which i must approved in order to block this client. Apparently a Rita James!!! Im sure MTN wont do simswops on our accounts without your ID proof and that somebody cant claim that somebody elses cellnumber is theirs???? Please confirm if this is spam??? I told her im not approving any OTPs and i will go to the MTN office myself to report this so called simswop.