Overbilling, Slow Internet Connection, and False Advertising 10mbps deal!!!

Telkom has done it once again, despite my repeated complaints regarding the fact that I did not have internet connection, this time they have sent me a big invoice for 2100 which I have no idea what it's for, and will certainly not be paying that. My internet was installed last month, and it has been off since inception. The only day it was on, it was very slow and disconnected often such that I called them and they tested it and informed me that they would need to send someone to fix it. Since then the internet has been down and off till I complained again on 21 June 2018, which is when they sent me a technician that advised me that the connection was off because it had a problem, and they fixed it, and they increased the speed to more than 5 mbps. When I asked them why only 5mbps, I was advised that I will not get 10 mbps even though I selected that option, and since then the speed has always been 5 to 6 mbps which is also frustrating esp when you signed for much faster speed, why false advertise? Further, the invoice must be prorata from 21 June 2018 to date as I had no connection prior to that and on the one day which I had connection it was at 2mbps. This is utterly unacceptable and I will not tolerate being taken ride by Telkom!!! Rectify this, and ensure that i get the speed which I had signed up for, otherwise you can take your internet!