Complaining

I'm so surprised my number disconnected on Thursday aroud 5pm while busy working my network witched off, immediately I called MTN customer service they told me I have not been using number for past 90 days but I have been buying data,airtime with a bank and making calls everyday with that simcard because I registered my business with the same number it's four days now I can work or due any transaction because my number it's not working anymore which I started using 17 years ago