Fibre WiFi Router problems

I have signup with MWeb for the Fibre package at 809 per month free router and installation. We have received the router model WR7010v2 on the 15 May 2019. We have set up the router with the help of MWEB technical. A week later we still have problems, when my son contacts them this morning the 24/05/2019 they told him that it might be a setting problem and change the setting after that the WIFI was even worse. My son also told the guy that the rooter that they supp**** to us compare to other service providers are terrible. I have sent a mail to technical as well this morning no response. Then I contact technical again and they told me that this specific router reception range are only 10-15m really. My son went to get some info at our local computer store, and they told him that we need to get an extender to get a better signal to the rest of the house and will cost us R650. I told the technical guy that this is what the guys on our side told us and he said that that will be the only way. My question to the person was why are MWEB selling these routers then, and why did the sales person not told me that the router will only work in a 10-15m range, and why must I pay so much for the duration of the contract as I must still purchase extender to get proper connection. I then contact the billing information to find out how to cancel the contract and the call was dropped.