It seems the supplier only communicates with others in its own company by computer and they failed in this instance. You could say they, "couldn't organise a piss up in a brewery" as my old dad would have said. I certainly get very fed up with communicating with computers! All their letters seem to be generated by a computer and, one day, it will be very hard to find a real human being to speak with.
Ever since then, I have told them to go away when I get emails offering me fittings. Now, I have little doubt that, used intelligently, these could save money, but I shall wait.
My bank is similar - a while back it took 3 different people 33 minutes to explain something that should have been made clear in a letter I had already received. 2 of these calls were with an Indian call centre. Now I have no problems with India - indeed these people tried very hard - but I do object to being a faceless number. Years ago I could walk in to my local branch and speak with the manager who actually knew me and cared! I'd better stop as I sound like a grumpy old man!!
So, I read with interest some links copied to me by Steve G1KQH which are below.