Re: No show that won't appear in statistics
The reason why they didn't tell you that the exchange/cabinet work hadn't been done was because the department that does that work doesn't have a process for telling the installation department that the work has been rescheduled. So the people who call/email you have no idea that your install can't go ahead, and may only have found out themselves when the engineer goes to the cabinet that day.
This is exactly what happened to me twice - engineer turns up at my house only to discover that the cabinet hasn't been upgraded. The second time it happened I was insistant that they didn't even schedule the third visit until they had confirmation that the work on the cabinet had already been carried out, yet I still got a call a couple of days before the cabinet work was due trying to insist I could make the appointment as the work was definitely going ahead. Guess what? It was rescheduled again to "some time 2013" (bearing in mind this was going on over a year ago).
Like you I received a generous £10 per failed install and I had to argue for that as technically they HAD called, just not been able to carry out the work, which makes that payment discretionary!