Telkom billing is a cheat

I have a 24 month contract with Telkom for Wifi 40 gig day and night with a R1 limit, end of May 2019 I got a bill for an extra R290 out of bundle charge. I queried this twice and was told it has been resolved, I used out of bundle according to them. I cannot use more gig than i have as it tells me out of bundle and I have a R1 spending limit and they keep telling me but i used out of bundle, I have tried calling Telkom, I have tried their chat online which goes off line all the time, I am in a contract but they can charge me whatever they like, this is not fair