Data disappearing

I called Telkom a couple of weeks ago to complain about losing an enormous amount of data in a very short space of time from my wifi router. After the call centre agent imp**** that it must've been all used up by me, he said he'd have technical support get in touch with me. They have since failed to make contact with me, and I'm still losing data at an alarming rate so now I just switch my router off completely since changing passwords doesn't even seem to help. I lost over 5 GB in 2 hours on Saturday morning and I was fast asleep at the time with my device off. Telkom doesn't seem very helpful and it's extremely disheartening and frustrating that I'm getting no co-operation from my service provider.