Axxess capped data disappearing. No help from support.

I've got a 300GB capped Vumatel Fibre line (20/2mbps) with Axxess. I usually never even start using my current month's data, because of the 3 month data rol*****, which means that I end every month with more than 300GB unused, which then rolls over. This month my data was depleted.

Long story short: My data has been "disappearing" from August at a rate of between 500mb and 1gb per hour. I did not notice this because of the large amount of extra data I have. I deduced this by going through the hourly usage logs provided by Axxess, and noticed data disappearing when I was sleeping and at work despite all devices connected to the router being switched off or not present at home.

By process of elimination I deducted that this is an error on Axxess's side, because after switching off my router between 20:30 last night and 10:30 this morning I had 6gb less.

(And yes, I did change my router password to a new 25-character-password, switched off WPS, SSID broadcasting etc. So this is not a case of a device using my data, especially since I switched the router off and still lost data)

I have phoned and talked to consultants 7 times already, and each person tells me the manager will have to phone be back. The last consultant transferred me to the manager, who then picked up and put the phone down in my ear. I have also emailed and logged a ticket, and nothing has come of this so far. No one has contacted me or offered any solution.

I also bought 40GB of extra data (for about R300) 3 days ago, which is also now depleted.