not getting my minutes and data on the agreed date

I'm sick and tired with the poor service from mtn, I have a contract with them, I'm suppose to be getting my data and airtime every 20th of the month but every month I don't ge the service I'm paying for on time so I end up having to use my money to buy airtime and data which takes me out of my budget. They always deduct my money on time but for me to get the service they are always late, even on their customer center I can't get hold of them. This is annoying and this is my second complain about mtn in a space of 1 month but it like hello peter does not take this issues seriously. Mtn your service stinks, can't take this anymore, if possible can I cut tires with mtn