If this is from Richer Sounds, I think this is a bit of a myth (the 28 day refund option).
I enquired about one of their amps recently, querying if I can return for a refund if I don't like it. The salesman in their Edinburgh branch said I was welcome to buy and try it out at home, but an exchange was as far as they could go.
Not looking to cause a ruction here, but 28 day home loans and sale or return aren't really their thing. It would be quite good if it was though! The 28 day limit is one of the consumer rights that you can return an item for a refund if it is faulty but after this time, a retailer is within their rights to offer you an exchange.
Since, it comes to light that consumers may have longer in the event of a fault, but the onus is on the buyer to prove the fault lies with the machine they've purchased.
Bit of a grey area all round I think, but ultimately, the option to return and expect a refund within 28 days isn't always the case in the event of simply not liking the item.