Vodacom won't help find sollution or answer.

I have a 3 gig Wi-Fi mobile modem @ Vodacom, that I have on my person at all times.This is used mostly to receive whats-app and was hardly used this week.I didn't go on the Internet, or facebookc.However yesterday, the 8th, I received the message that I need to re-charge. I called Vodacom Active and told my story.They referred me to Vodacom Technical support I was advised to go to our Vodashop for a itemised bill. @ the Vodashop in Secunda Mall, the person said that it is pointless because you will not be able to see any thing.He helped me to go into the site to see if there is any other devices using our data, which I commend him for.But they had no other suggestions,I was assured that this is a safe connection, however either that is not true, or they are not giving me the data that I'm paying for.Unfortunately I'm not able to prove either way.We had 3G's in the past, and no coverage.Were bound by contract to pay for service we didn't get. We reported it repeatedly, however nothing changed and Vodacom wasn't willing to forfeit the contracts despite the fact that we could not make use of the service we were paying for...