Billing error

The last 4 months MTN is deducting double my premium of my data contract. The 1st time I called in, I was told I've skiiped a debit order. I told the lady that my debit order was up to date. The 2nd time I called I was advised that MTN changed over to a new system.... And that I Should reverse the debit order and pay it directly to MTN... I've done this. My number got suspended and I had to call again. ( reference # ***) The 1st of July the same problem, but now I get charged for reversing debit order... Who's fault is this? I went in to MTN in Greenacres, I was helped by Melissa... I was told that I'm not the only one, there's lots of customers complaining about their billing..... I'm still waiting for her to call me back. Yesterday my number got suspend again.... Latest reference # : *** ansld was helped by Nokwanzondo

My debit order is R200, this is what my contract states.... MTN debits R400 a month and the last debit order amount was R411.

I've been a loyal MTN customer for years.... The service is pathetic!