Simcard Bill

I took a Simcard contract with Vodacom few months back, everything was fine, until they sometimes decide to not debit, and then i must pay double or triple the amount, i asked them 2 months back to update my debit date to the 23rd, the assured me its updated, to my surprise again Incompetence, they did not debit last month which now i must pay double because of their incompetence, how can a simple thing as changing a debit be date be so hard, the service is appalling, i asked them to get back to me, they took my number no one has contacted me thus far, are they running a business or a ****a shop because wow, the service is really way way below standard should have just stayed with telkom, Vodacom is expensive for nothing