Mtn is a disappointment

I opend a mtn Data contract about 3 months ago. I only wanted to use the data for work as for the work with lockdown has beet still i did not use the data at all. I got a message today saying if been handed over for non payment. I did not get any call from then. Any mesage. Any email nothing. Hell i did not even know the debt oder did not go off. As there is always money y in my account. To get in touch with them is nearly impossible and all the Numbers online is not working.