MTN ****

I received an unknown call from someone identifying as MTN anti **** dept telling me someone tries to duplicate my simcard. He instructed me to swipe on my iphone and submit a TPO which I received two different TPOs. I said I can not just trust a caller. The caller got aggressive and said he will cancel my contact. I told him I don’t trust the situation and stop the call. I reported this to MTN help line. I received a bot answer that this will be followed up on first working day. It is a very concerning call I received. What to do in future???