Taking time to debit the money on my account

I have been calling cell c to debt my money on the first of every month the last 2 months cell c was not debiting money on my account 8 was not even aware because I always have funds for my debt orders the day they blocked my Sim that is were I realise that something is wro g I called they said I haven't been paying I told them to debt the money that I am owing they did but now still they haven't debited the money still today everything I have to call them to debt when I made arrangements that they must debt each n every month the service is poor really disspointed