Super bad service

So i decided to get a LTE router for my home, cell c high veld mall assisted me with this and gave me a LTE sim card and the works(after they have checked if we have LTE coverage,and the laddy told me that we do).

So i went home and started to set everything up, only to discover that we dont have LTE coverage in my area. I went back to the branch and explained to the what my issue was and after a few arguments they canceled my contract and issued me with a new one.

i went back home and everything went perfect for a few months till one month i received a out of data charge (R500) so they never changed my limits according to my 1st simcard they have issued wrongly to me(as i did ask the Branch manager to please make sure my limits is set to what it was). Needless to say i refused to pay that R500 and i went to the branch at least 3 times a month to try and get this resolved and every time they promised me that they are working on it and that it would get resolved.

6 Months in still nothing, they debit between R880-R990 a month and i am paying money for a service i cant even use, they just suspend my lines month after month in a total of almost R5400 i have literally payed for nothing...

now they told me that they will pay the R500 that was outstanding but as for my R5400 they cant do anything.. and my account is still in arrears.