Vodacom at it again!!!!!

Vodacom promised me 9 GB of data with my contract which they have been giving me month after month, today they decided to downgrade it to 4 GB. Their systems are so backward, apparently they cannot see that they have been giving me 9 GB monthly and suddenly it is 4 GB. Now I have to wait for my data as they log a call to retrieve the contract recording for the second time. I know this is a lengthy process. How about this Vodacom? Why don't you pay attention when signing contracts and give your customers what they agreed to instead of putting them through the monthly ordeal of dealing with your Customer "service" department?