Data has fallen

I am a prepaid customer with Vodacom , I am also a business owner who relies on whatsapp for communication with my team when they travel across the border , My account was credited with data that I did not pay for & when I brought this to the attention of the sales assistant at the vodacom store at Northgate , the response was to be grateful for the data & use it. So I proceeded to so , until I received an sms from Vodacom stating that my account had been credited incorrectly & that they are sorry for inconvenience, the account was restored , but It's a not my fault that your system has forced this error , it's a problem that we cannot carry over data , so not only do I loose the data that I have not used which translates to money for me but I also have to spend more to get data, so it's a win win out come for Vodacom all the time, now that Vodacom has sorted out it's data problem , it leaves me with having to go out & buy data, but why is the sales person so blase' they could have notified Vodacom about the error not tell me to go using some thing that is not mine & be fine with it, totally unprofessional & no compensation for a mistake that was not my fault..