Are you including line rental in that? If so, sounds about right, if not you’re being done 🙂
I’ve been with PlusNet for years now, they own my phone line too (for the 7 calls a year made on it). Bill is normally around the £30 mark, but I get a bit of discount from referrals. I can send you a referral if you like ;-D
They have been excellent though. I get (real) 6Mbps / 448Kbps up on a max possible of 8Mbps and they have worked hard with me when I had a lot of issues (resulting in getting BT to change my star wired main socket to NTE5 for nothing).
Have you tried changing your router? Have a Thomson somewhere that is supposedly very good on noisy lines (bit old so has only 54Mbps WLAN, 100Mbps LAN ports) if you want to try it?