I think that you have left it a bit late for demanding compensation. When you approached their customer support, you was given advice satisfactory to the problem in hand. Perhaps if you had approached Watford, when you had the original problems, instead of taking the matter into your own hands,then this question that you have raised, need not have been required.
Do they know that you may have invalidated the warranty. Some companies, allow the customer to upgrade, and only invalidate the warranty on the parts the customer as fitted and supplied.