MTN no service

I am using MTN for several years with no problems. I have a contract to provide me with 500 minutes airtime on the 5th of every month. Everything went smoothly until 5 April 2023. Suddenly I am told I ran out of airtime just after the 5th, and had to buy airtime but my subscription was staying the same. I tried everything possible on their website but can't get a number to call or any place to try and correct the problem. I went to their shop in The Kolonnade, Pretoria but they could only say that their is no problem and could not help. At this moment there is no one and nowhere I can go with this problem!!