SIM Faulty

I have been having 2 contract phones with Mtn for years now, and have been a loyal customer to them, I lost my phone and did a sim swap, them a month or 2 down the line the sim card is no longer working, It kept giving the error that I should enter simcard, I thought it was my device but unfortunately its not, when I use a different mtn macro sim is work fine, I went to Mtn in Klersdorp and I was told to pay again for a new micro sim card, I was expecting them to take their sim and gave me a new one without paying as I did not damage it, it just decided to mulfuntion properly.<br> <br> I would be very happy if mtn can replace my micro sim card without paying, I am currently resides in pta, sunnypark branch is the nearest. Your customer service would will be highly appreciated