As said, UK consumer law is very good. A product has to be fit for the intended purpose, and if not, you are entitled to a full replacement or your money back. You can always indicate that you will pursue them through the small claims court if they do not provide satisfaction. That might get them to take you more seriously. After all, a camera that repeatedly fails, and which you cannot use because it is being repaired, is little use.
There are also some trading standards web sites in the UK. I'm sure a Google search will find them. You could also contact your local trading standards officer. They were very helpful to my late mother when she was preyed on by sharp salesmen.
Leif