Yes. The worst that can happen is that they say "no". Trying to bounce the credit card payment should only be a last resort as if you try it too many times, your credit card company will get annoyed.
The only time I took something back to Dixons was when I bought a camera from a man who had bought it from Dixons a couple of months previously. When it stopped working I took it back to Dixons and they replaced it with goods to the same value without a quibble.
I would recommend everyone keeps their receipt. We just use a bag under the kitchen sink. If ever there is a problem, we have a good root around in this bag for the receipt and take the goods back. It's no great trouble and it saves a lot of worry. I honestly take "lifetime guarantees" with a pinch of salt but having the receipt puts me in a good position to return such goods when they pack up years later.
Of course there are retailers who don't care about the customers. Years ago I bought a duff tape deck from Laskeys, took it back several times and each time they claimed to have fixed it, but they'd done nothing. Eventually the guarantee ran out and I stopped taking it back. They kept my money but I never bought a thing from them again. Also I told a fair few people. Today Laskeys are, I believe, not trading.
In contrast I recommend Miller Bros, Asda, Jessops and a few others. I personally don't mind paying an extra couple of pounds if I know I can return something.