Vodacom Night Owl non-existent

I have a contract with Vodacom on a 40 Gig plan for R300 a month. Split between 20 gig day and 20 gig night. For the past 2 months I haven't been able to use the 20 gig at night (12 am till 5 am). It just doesn't connect or just goes annoyingly slow (like 5 kb/s). My day time would be depleted, which is okay. It doesn't make sense why the night time would be affected.

Calling the Vodacom help-line was no help at all, I was sent from one un-helpful person to another. I can not even access my account to check my balances, it just takes me to a FLEX page that's not helpful at all. I have never missed a payment and I pay for the service in-full, therefore I expect to receive the service in full. I have no problems with paying half the amount for half the service if this problem persists. Please somebody sort this out!