Hi
That must have been frustrating!
A couple of tests you can do for your-self.
Remove all other devices you have plugged in to other phone points and see if your connection improves. One of your devices could be causing trouble. This happened to me, I had a device which was causing our connection to slow.
Try replacing the phone lead from your point to your modem, the shorter the better.
Try plugging your modem into a different phone point and monitor. There could be an issue with your internal phone wiring.
Good luck.