Sounds like you may have some sort of problem with your line, which you would just take with you to another provider. It's the same wires to the exchange/cab whoever you are with.
It's not clear if you already have fibre, in which case with that speed you must raise a fault as something is seriously wrong.
If you are waiting for fibre and have standard ADSL then it will be affected (as will any broadband) by line problems,. so the Exchange DLM (Dynamic Line Managment) will ultimately slow your speed in an attempt to stabilise your connection. This is an automatic process over which no ISP has direct control.
The best place to start is have a listen to your phone line, do you hear any crackling or other noise when using the phone, or have any problems making outgoing or incoming calls? This would suggest a probable line problem - who do you pay line rental to?
Do you have any fixed extension sockets and wiring? Are you using any extension leads? Do you have a
Master Socket that looks similar to the one on the Left or right.
Is every phone, sky box or any thing else plugged in by
Microfilters look that like this
