Terrible internet connection after assurance of coverage

I was assured by Telkom that there is LTE coverage at my specific address and I therefore signed up for a wi-fi contract. Unfortunately I am now stuck without any internet and on occasion, when I am able to connect it is slow and constantly interrupted. Had Telkom been upfront about this problem, I would not have signed up. How can Telkom expect that I pay a monthly fee when I'm not receiving the service that I am paying for. Surely you are not living up to your end of the contract.

Another surprise came when I received my invoice. In store I specifically asked if there will be any subscription or activation fees involved. I was told no, only the montly fee will be charged. I clarified, to make sure and was told no other fees besides the monthly fee will be charged. Yet on my invoice there are at least 2 subscription fees added.

So I would like to know how I can be expected to be held to this contract and continue paying every month when I am not receiving the service that was promised to me.

Also, does Telkom think it is acceptable to give incorrect information to their customers in store?