Outgoing call blocked by MTN ads

Within the last few days I had 2 outgoing calls effectively blocked by MTN adverti*****ts. I did not ask for this , as a matter of fact , I left all the checkboxes for correspondence unchecked except for email, when I renewed my contract. <br> I know the call is blocked because I disconnect when I hear the add, and the person on the other end did not receive a missed call notification. I know that the other networks don't do anything like this. Please remove me from your spam list! I am already a MTN account holder.