Think you meant to say router 😜
Have you tried an Ethernet connection?
For wifi have you split the bands? You can also do a factory reset to the router.
We are all customers like you here; Now employees do not engage with us on the Community. And even if they did, I doubt they’d call you 😢
But you can call them, for Broadband issues like this. On 150, if you have a landline telephone handy.
Or on one of:-
0330 041 2518, 0330 041 2462, 0330 332 3050, 0800 759 1213, 0330 041 2473
I suggest that you be able to quantify ‘incredibly slow’, as a percentage of the speed you were guaranteed, and it will help you to avoid Now passing it off as a WiFi issue if you can measure it on a device wired to the router with an Ethernet cable, if you can. Otherwise, ensure you have a WiFi speed measurement taken as close to the router as you can physically get.