Welcome to the forum.
Log into your router from a browser at http://192.168.0.1 (username and password is admin and nowtv unless changed) then go to the Maintenance tab. Here you can see the upload and download connection at the router.
If these look OK it's probably not an issue with the line and may be an issue with wifi performance instead. Try rebooting the hub as by default this should make it choose the best wifi channel for your environment (unless you’ve previously chosen a specific wifi channel for it to use).
You might also need to experiment with placement of the hub, generally speaking you want it as central, as high up and as far away from electrical interference, metal obstructions and solid walls as possible.
If this doesn't improve things, give the broadband team a call (free from your home phone) and they can check things out for you. You can find the telephone number for the Combo Team by going to your My Account > My Package page
Not sure what time they close on Sundays so might need to be tomorrow if you don't get through.