'Never knowingly undersold' is bollocks to make you think that JL is cheaper than elsewhere, when it isn't.
Desolate says she has had 'countless' price matches, which means that all these items were more expensive than elsewhere until she asked them to price match. Did that cause JL to lower their prices? I doubt it, even though by giving someone the price match, they are alerted to the fact that they are more expensive. I bet plenty of other people paid the higher price anyway.
People go on about the service and the warranty, but in my experience, electrical goods are pretty reliable and last for many years beyond the warranty anyway, and if they do break, you've got your statutory rights anyway. Things should last a reasonable period, which is usually 3-6 years.
When our 13 year old, bought from Curry's dishwasher died, I looked at Currys and JL for the cheapest available Bosch replacement. Currys were £50 cheaper and could deliver the next day. The one with the same features from JL would have taken a week for delivery and as it had a very slightly different model number, they probably wouldn't have price matched anyway.
I'm not waiting a week without a dishwasher and going through the hassle of a price match that they probably wouldn't honour to buy from JL to get a warranty that I'll probably never need - said dishwasher is now at least 2 years old and used daily without any faults anyway.