I've been with IDNET as a purely broadband customer for some years now and have had literally faultless service. I switched when my previous ISP went bust. The only time I needed to call I received an immediate response and patient helpful advice with the IDNET expert staying on the line until my problem was resolved.
I had retained BT as my calls and landline provider until they dramatically increased my line rental because I wasn't using their broadband. As of today I use IDNET for calls, landline and broadband. The switch has been pretty seamless; I needed to re-boot my modem that's all. I'm saving money and I am with an ISP I trust.