Prepaid problem?!?!

[Hellen]

I installed a prepaid meter about a year ago into my newly built house
in Celtisdal a Centurion subburb.
At first I did not experience any problems but recently I have
realised that my meter has been running faster than usual.
This all started about 3 weeks ago when my prepaid electricity was
terminated because, according to the municipality, we were in arrears.
Can u believe it!! prepaid electricity in arrears!!!
I phoned the municipality and after a long discussion they determined
that I actually was in credit with them.
They said they will immediately send someone to activate my
electricity, needless to say I waited for four hours to arrive.
I started to monitor my meter. I always used between 300 and 450 units
a month, all of a sudden I am using more than six hundred units per
month!! What is going on? We are two in the house and I am paying more
than 100% more for my electricity this month as 2 months ago??
I can understand that the rate per unit has increased but why increase
the speed of a unit???
Please help me to understand.