MTN Data Contract a constant problem

I took out an MTN data contract in September 2014 selecting a debit order date of the 15th of every month. From inception of the contract to date I have had issues each month regarding payment for the services and my services being suspended. Initially, MTN would attempt to debit my bank account within the first 4 days of the month as opposed to the agreed upon debit date of the 15th. As I had minimal funds in my account at these times due to the fact I had not received my salary, my account would go into overdraft resulting in bank charges. MTN would subsequently deactivate my services. After 3 months of this and dealing with the call centre, the problem still could not be rectified so I cancelled my debit order deciding to rather do an eft once I received my salary to work around this issue. However I now receive notifications from MTN instructing me to make payment by the 4th of every month. I reworked my budget in order to make the eft's before the 4th, receive a notification from MTN that they have received the payment, and thereafter my services get suspended. Every month I have to call the call centre (a 30 minute process) to have my services reactivated.