Account locked even though I never miss a payment

Hi - I have a query please - I have a number of Vodacom account and spend an average of R4000 - R 5000 per month on Vodacom - but for the past 4 months my accounts are being locked everytime - even though none of my Debit Orders fail or return.<br> <br> Thus I am paying my account - it is up to date - even the Customer Support says they do not understand why - but I am without a phone and Internet at least 6-8 days a month because I am non-stop on the phone with Vodacom support to try and resolve the problem.<br> <br> I understand there are out of bundle rates - but still I have a debit order? So what exactly is going wrong?<br> <br> Thanks for reading!