It’s working perfectly! The man who came out sorted it an said the older ones tend to seize up. The newer ones have had a design tweak, so it doesn’t tend to happen anymore.
I’d just like to say your customer service is absolutely fabulous and I’ve been recommending you left right and centre. Make sure you show your boss this email. Staff like you who really care and follow up problems are gold dust!
Thanks again for all your help!