Long time customer treated poorly

I have been a longstanding client with Cell C for 11 years and yet I phone for assistance today and am just treated with such disdain. I'm stunned. I have phoned them twice to move my debit order date due to moving companies and they just argue and say sorry, can't help this month, it can only change next month and now the same issue so 2 months I have a bad record because even though I phoned they insist they will debit on that date.