I have BT both at home and work and it's very rare to have a problem and when we do it's resolved very, very quickly. My office is very rural but we receive good speeds and a very reliable service. For phones and broadband BT have been excellent at work but I would never give them more.
My one business experience with BT was very poor; several years ago, perhaps 5-6, I was persuaded to switch our ISP, email services, domain etc. to BT. It was a total disaster and left us with zero communications - after 72 hours I had to go back to our previous ISP and ask them to solve the issues, which they did in a matter of hours. We are only a tiny company and our account is worth perhaps £100pa to the ISP. I love those people.
At home we have BT phone, broadband, Vision and soon will get free sport. I probably pay more than necessary but it works ALL the time. Like the poster above I do get irritated by the special offers to new customers but it's the same everywhere from banks to gyms to car insurance.
Customer service is in my experience very good. About three years ago we began to suffer problems with BT Vision. As the product improved and required more speed our received service declined. I called BT, explained the issue and that I needed them to install new equipment, initially I was to be charged but when I pointed out the main incoming socket was stamped GPO BT agreed to send an engineer who replaced all the sockets in the house free.
BT Vision has just had a major software upgrade which has bugs and is taking a little time to get used to. We watch the various iPlayers via TV, laptop, nexus 7 or iPhone as takes our fancy. Following the new upgrade we suffer so much buffering with BBC iPlayer it is unusable on the television - everything else is fine. Our TV is 1000p but the best resolution we now achieve is 720p.
I called BT at 9.00pm Bank Holiday Monday. The "Indian Call Centre" slightly derided above immediately agreed the 1000 / 720p issue is a BT problem and they are working to fix it ASAP - BT admitted the problem which is a big plus for me. The lady attempted to solve our BBC iPlayer issues but could not and offered to escalate this to level two, saying we would have a call back in 24 hours.
The call back duly came inside 24 hours, the technician immediately agreed our view that as we had made no changes and all other equipment still worked the issue had to be with the BT software and probably it's suitability for our BT Vision box. In the same conversation the BT technician organised a new box, FOC, and insisted an engineer be sent, again FOC, to check our incoming sockets, connections etc. All this was offered, no arguing from me.
As a Total Broadband customer I can use BT WiFi virtually anywhere which is great. I travel a lot for work and get sick to the back teeth of all the "free" wifi offers in places which require to spend minutes signing up to a service which is going to spam me when all I want is to check and email or surf for a few minutes over coffee!
If that's not outstanding customer service I don't know what is.