I had my experience of a dreadful engineer visit for the fixed wireless ISP I've now cancelled, which were probably contractors. When they arrived, I tried explaining just how slow and intermittent my connection has been for the past couple of months, but they told me upfront - "If we see Internet connectivity from the antenna, there will be a service charge for this unnecessary visit!". They did not care that the connection was erratic, upload speeds dipping below 100kbps (for a "10Mb" package), etc. It was only for the fact I saw they had trouble loading up speedtest.net (page kept timing out) that I managed to escape the call out charge, where they basically accepted the connection as being fixed by a software upgrade on the antenna. After that, I wrote to cancel the service and recorded a 10 minute demo video of the connection acting up trying to do just basic web browsing and stuck it on YouTube.
While visiting relatives in San Francisco, they asked if I could help them extend the Wi-Fi coverage through their long house. I suggested getting a pair of HomePlug adapters, where the second unit acts as a Wi-Fi access point, but they were convinced they would not work. So I asked why they think that. They said that Comcast told them that due to the length of their house and the limited Wi-Fi coverage, they will need a second Comcast Internet subscription to provide Wi-Fi coverage at the other end of their house.