Proof of payment

I am unhappy with the way DSTV is treating my moms account I pay her account every month but this month they keep on saying they did not receive payment when I did pay even though I sent them proof of payment from my bank statement and from my bank as well (nedbank) multichoice keeps on saying the account has not been paid even if there is proof of payment. Now they have suspended moms multichoice account and that is not fair at all.