Data Dissappearing

I logged a complaint with Vodacom in the beginning of the month when my monthly 3 Gig that lasts me usually the whole month dissapeared the same day. Vodacom then gave me back my data and I didn't use any internet for 2 days. When I went on the internet 2 days later once again my 3 gigs were gone. I have bought R99's internet on the 1st of March, then on the 4th after my 3 gig that Vodacom gave back to went missing I bought another gig for R149, on the 15th I had to buy another gig for R149 and then this morning I bought another gig worth R149 from my phone when I was not home so not using the internet. When I got back home now the gig is gone without anyone using it the router wasn't even switch on. I had to buy another R99 just now again. This is really starting to get my back up. When my first 3 gig went missing Vodacom checked that I don't have updates running and they asked me to change my passwords and id which I have also done. It is absolutely absurd to keep on buying and as I said no one was at home to use the 1 gig I bought this morning and now I had to buy again. Please rectify this ASAP or cancel my service with immediate effect.