Wifi Slow?

Hello,

For the past 2 days, the wifi in my flat has been horrendous. This is something that we have always struggled with; it's a 60s build and the walls are thick. We have 2 pods around the flat and this has always been sufficient.

Now, in the room furthest from the router, the office, the wifi is unusable - with the pods, we usually end up at around 100mb in this room. At the time of writing, the speed is so slow that a Speedtest cannot even register a minimum speed. I have tried restarting the router, changing the pods around, but to no avail. At times, the speed on the speedtest will be variable from 20mbs and it will jump around frantically before settling on around 0.04. 

There is nothing wrong with my line, indeed when in the same room as my router, I achieve around 300mb at wireless. Something has changed and it's not something physically within the flat but we don't know how to resolve the issue? 

Interestingly, the issue started immediately after a phone call from virgin about the end of my contract coming up soon. Literally immediately after! I'm not suspicious of these things, but the timing is humorous to say the least!