Oliver, are these the binoculars that you bought?
High contrast BBFMC.pdf
If the product is "Not fit for purpose" you should be pursuing a replacement via "The Department of Fair Trading".
You purchased in good faith and it is not you resposibility to repair the goods.
Your posting is timely as I have been considering a different model of Binoculars from Andrews. I will be interested to see how they ultimately resolve the issue with you before proceeding with what was to be my first purchase from them.
Michael