I'd be inclined to suggest they let you have a loan tv to equivalent standard while they sort it out at their leisure or alternatively give you either a new replacement f.o.c. or a high allowance against a new one
I'm sure it's easier to keep them on side (bearing in mind most manufacturers do tend to have a habit of ignoring the end user all together, leaving you to battle the uninterested retailer) by being fair and polite yet firm, pointing out that one of the main ideas of buying their product was in anticipation of the World Cup, and you feel sure they will take this into account
10 months down the line they are doing the business but may well go a little further if requested. Remember, once they get to the stage of concluding there is no goodwill to be gained by spending more on solving the problem they could go into the "We are going to get the "I'll never buy another..." from this guy so we might as well go into "What's the least cost to ditch this problem?"
You could go down the trading standards route but quite honestly it's just the sort of thing to wind you up daily and, in my book, there really is more to life at the end of it. If it ever got to that, I'd be going to Richer Sounds or John Lewis, take your pick, buying another, and selling the original for what I could get once it came back working
Hope it sorts itself out for you