Incorrect Billing

I spend an excess of R3000 per month with Vodacom - In anyones books that makes a very loyal customer.<br> On 1st of April I purchased a 10 Gig Bundle for R599 for the new month of April. However Vodacom has billed it for March, thus causing my bill for much to have an extra R 599 charge for March. Vodacom is now telling me they cannot put the 10Gig bundle charge for the month of April because the invoice is already generated.<br> I have proof that I Purchased this bundle on 1st April and I don't understand why Vodacom wants to bill it for April. <br> This is something I do every month(purchase a bundle on the 1st) and I don't understand why I have a problem on this particular month. Its clearly a fault on Vodacom's systems and Vodacom is lacking accountability. I demand that this 10 Gig bundle be billed for April and not March. SR - GSP2Q-QVFOI