Last in first out depletion of data,minutes and sms's

As of April my contracts have been depleting on a last in first out basis. I have been to Vodacom in Heidelberg Mall and could not be assisted and I also lodged a complaint with Vodacom customer care about 4-5 weeks ago. Yet no assistance regarding this matter. I have 6 contracts. I don't even know how many minutes and data was lost over this period of time yet when the bill comes they are sure to debit your account.