I just wanted to give a public thank you to a really helpful vendor.
I purchased a dynamo bracket from http://www.reallyusefulbikes.co.uk/, but unfortunately the wrong item was dispatched. The item sent is of a different design, but would have done the job just as well.
However, when I contacted them, they couldn't be more helpful. And I only really contacted them to let them know the item I received matched a different picture on their site. I didn't ask for an exchange of the part, as it would have worked just as well and was the same price so it didn't really seem worthwhile to go to all that trouble.
However, they have sent the correct item, plus a few bits "I might find useful" and said to keep the incorrect bracket as well.
I know it is a low value item, but the sheer level of helpfulness and goodwill for one little item was unbelievable.
So Rob Bushill and Really Useful Bikes, thank you very much.