Safricom Telecommunications Potchefstroom (Bad service from day 1)

On 24 March 2019 Safricom came and installed wireless internet. On 24 March 2019 I mailed the sales agent and explained the internet is very slow, I signed up for a 10mbps and only get 0.8mbps and that the signal is weak. I told the sales agent on 24 March 2019 that if this is something I am going to struggle with they should come and remove the system. Nobody came to fix it and on 3 April 2019 I had no internet and I asked for them to come and remove the device. I sent a mail on 8 April 2019 explaining that I will not go on with internet service. After a lot of e-mails and phone calls I finally received the cancellation instruction on 23 April 2019 and send it back to Nienie, Johandre and the accounts department I explained that I won't make any payment for installation or wifi as I had issues since they installed it. And Nienie mailed me back and said she would give it through to the relevant department. On 25 April 2019 I received the statement with the credit note for installation and the Wifi. And that was the last of my correspondence with Safricom. So according to me it was sorted. Today on 21 April 2020 I received a phone call from Tina stating I owe them R3500 for the equipment (please note they came and collect it) I am really dissapointed in them and now they are stating that they did not came and collect the equipment and could not get hold of me. The irony of every thing is where I worked was in the same building just different offices of Safricom. So how could they not get hold of me.