I have queried the high postage charges twice, the first time when I had ordered a ring in two sizes, not knowing which I needed, and was shocked when they arrived together by Royal Mail for a total cost of about £2, even though I had been charged just under £6. Both times, they said it's simply to cover insurance, as mentioned above. I say that's bollox because if they were worried about loss, they could pay for Royal Mail Signed For which would give them full compensation.
I agree with the posters above who suggest they use the high postage charges to cover the free phone number and 30 day MBG but I still think there are three other main reasons for overcharging on postage:
1. They can - people keep paying the P&P so they are happy to keep ripping us off.
2. They like being able to quote the item price only on air - eg presenters saying something is under £35, when it's over £40 with the P&P added. (That's bad enough but what is unforgivable is when they say, using the above example, "You can get this home for under £35" because that IS a lie.)
3. It puts people off returning items - not only will you have to pay the postage to return it, but you straight away lose the extortionate postage you had to pay to receive it. We all know that if they charged no (or less) P&P, they would simply increase the item price to make up for it but that's not so good for them because then if you returned it, they would have to return every penny you'd paid.
It will never change!!