Horrible internet for the last few weeks

My internet speeds have been absolutely atrocious the last few weeks. The first time it sorted itself out. Now since last night my speed is below 3mb on a 30mb line. Chat to your bot on Whatsapp and Rain cannot connect remotely to reboot. Surely that should tell you that there is something wrong. I have switched the router on and off on multiple occasions, and this does not resolve the issue. I don't need to move the router as it is in the same place it always is.

Please sort this out. I am paying for a 30mb line.