haha yes, they are sending me one anyway and charging me £5 for it also
tbh probably need their router should things go wrong as these ISP will always default to your own equipement being the issue as opposed to BT Openreach being the issue. Which is 9/10 times, BT openreach is the problem. so having their router there for debugging process is good idea.
I cant remember which ISP i had run in with that insisted the openreach/BT infrastructure has no fault (might have been Plusnet), and insisted on something wrong with router. when tested with their own router, it was the same problem and they actually sent me another router to test also. that was a massive waste of 1 week of toing and froing. at the end of it all, a BT engineer came down and found the line was way too noisy from cabinet to my house and switched the line and put a new socket in at my end and problem gone away.