Soooo unproffesional

I am very dissapointed in mtn, i am a current client with a cellphone contract. I fell behind a month on payment but paid it up to date the next month. But after one of their consultant phone me from their accounts department that assured me that i am up to date and the debit order for the end of the new month will only be R251 then from the new month starting i will go back to my normal debit order amount was according to them not true.... now they still missing a payment after i asked the previous consultant three times to be sure aboit how much will go off, she assured me all that i mentioned above. Now how is this my problem if a person isnt qualified enough to do their work and give out the correct information???