Vodacom
High account and Payment arrangement ignored

I made an arrangement 2 weeks ago with Vodacom to deduct 3 equal instalments from my ridiculously high bill this month. This was not done and to my dismay this morning, I realised that they had deducted the full amount. They were to come back to me but never did.

I need to know from them what to do now as some of my accounts will not get paid as a result this month.