One thing to rememeber is that nooen comes to this forum to say everything is working, it is a forum for people that have or have had issues and so will always show BT in a negative light.
sadly however engineers not turning up is not that uncommon, had quite a few of these myself in the last year or two.
I would not imagine that you would get charged for another visiit, if the line is showing as not being active then it is clearly BT's fault (assuming that you have actually plugged in the phone 😉 )
You just need to call them and complain, I also thing you will be due some compensation for the missed appointment but it is a pretty low amount.
Exactly the same as what happened to me. Just rang and was told that there was a delay in the 'processing side of things' and that I would get a phone call updating me on the 26th, 'or maybe the 27th'.
Awful, awful service. I'm going to see if I can terminate the contract and get a refund on my line rental, as I'm not putting up with this.