Received a damaged item - wwyd?

[BootyMum]

I bought a wooden toddler bed guard, it was a Buy it now item and was listed as brand new in box, undamaged, etc. However today when I opened the box I discovered that it has a dent on it so I suspect it may be a factory second. Box and packaging seems to be intact and so I don't think it was damaged in transit.
I was thinking to contact the seller to let them know but was wondering what would then happen? For example am I responsible to pay for return postage - as it is a largeish wooden item it may be quite pricey postage...

they should pay the return postage costs, but there is no way you can enforce this

Thanks Madam, I think I would be happy with a partial refund as bed guard is fine to use but has been cosmetically damaged. And it wasn't particularly cheap, only around £3 cheaper than if I'd bought it brand new on amazon.

Does the seller normally suggest a partial refund or does the buyer? How much off would be fair?

I think I would probably be happy with £5 - £10 off [item was £30].

Thanks for your reply by the way!