Telkom internet fiber VPN connection problem

I have been connecting to our company's VPN for more than 2 years now over a Telkom fiber internet connection. All of a sudden, since 5 days ago, the internet speed has dropped to very slow or non-existent when I am connected to the VPN of my company. When I use another internet connection (not Telkom), I can connect to the very same VPN without any speed problems. This is a Telkom problem and it needs to be fixed fast or I'll cancel my contract due to non-service delivery. This is a big issue for me as I need to connect to the company VPN in order to do my work. I have contacted Telkom twice today and they said there is no limitation on internet speed imposed, from their side, if I connect to a company's VPN. Even after I had explained that with another internet connection the same PC connects correctly to the company's VPN, the one operator stated that it must be my PC that causes the problem. So she inferred that my PC is discriminating against the Telkom internet connection. Her name is Ntokozo.