Bad customer service

An agent from Altech phoned me to inform me that they needed to upgrade my old system. I was told that I was going to pay R139.00 per month. I agreed to the installation. After installing the system , Netstar call me and me emails that I owed them R2333.00 for installation. I disputed that and transcripts was played to me which was allegedly tampered with . No R139.00 or R2333.00 was mentioned. We exchange emails with the credit controller. Instead he sent me 2017 invoices that I needed to pay and which were paid in 2017. Netgear is allegedly involved in a **** of using the agents to phone customers and thereafter tie them into a contract