I bought a Sense on pre-order - it arrived 2 days later that it appeared on Curry's shelves, so no advantage in pre-ordering it! After 6 days the strap broke, I phoned customer support and after about a day of emails they agreed to send a replacement strap. After some consideration, I decided that if this was an indication of the build quality of a £300 device, I would instead return the whole thing for a refund. Ranf them today, and got an email with return instructions that required me to pay for return postage. Rang them again (more forcefully this time) and insisted that in the UK the Distance Selling Regulations and Consumer Rights Act require that I could return it at the SELLER's expense. The guy initially said no, so I asked to speak with his supervisor. He went away, then came back to say that he WOULD send a reply-paid label. So if you're returning something within 28 days, insist that they pay your postage.
