shocking service

I have had shocking service from mtn all day from the 6th up till today ,, I am still waiting for a FONE CALL as to why my unbilled balance states R3000-00 , new bill run Is now for the next payment due end of this month . I stopped all my charges and data purchasing when my bill was on R1800-00 why does your 135 service tell me unbilled balance R3000-00? furthermore my service line needed a upgrade to which you just terminated my services after a mail was sent back to you with the option I had chosen for new line. I want a call today or I will move to another service provider and take these fees up legally , there is proof on your side after R1800-00 there was no further data loaded or purchased on my side for weeks as I was waiting for the new bundles to be loaded yesterday which weren't even done !!