Well they read my post and as well as leaving a comment and emailing me to apologise, they offered to ring me to sort things out.
First I need to say in their defence that last November when informing them I wanted to cancel my licence and get a refund, I did it online for the first time and so never actually rang them......and more to the point, I therefore never informed them the house would be empty for 6 months.
BUT that doesn't excuse all the previous years when I DID tell them the house would be empty and still got letters and visits.
Anyway not to labour the point anymore, as a result of emails and a phone call today, I'm happy to report their customer relations staff, especially SG (you know who you are but may not want to be named here), have come up trumps and I have an email address, a phone number and a location on their web site to inform them when I'll be away in future. If everything works, I shouldn't return to a batch of letter and a note from a personal caller all warning me to get a tv licence.
I'm a believer in giving praise where it's due and so, despite it taking several years of frustration and annoyance, thank you tv licencing customer relations.
It's also good to know a blog post can get results. Try it sometime....you never know who is 'watching'.
Oh, have I told you about my annoyance with Ferrari....................?