If the item was faulty, damaged, wrong or not as described, the seller pays. If you changed your mind, you pay — unless the store says otherwise.
That is the whole rule. Everything below is how it plays out.
The seller's fault
Four of the six return reasons are the seller's: not as described, arrived damaged, wrong item sent, parts or accessories missing, and an item that does not work.
For any of these you should not be out of pocket for postage. If a seller asks you to pay return shipping on a faulty item, that is worth saying no to, politely and in writing on the order.
Your change of mind
Then return postage is yours, unless the store's own Return conditions say they cover it. Some do, as a selling point. Read that field on the listing before assuming.
A change-of-mind return also depends on the store accepting them at all — No returns means no change-of-mind returns, though it never stops a faulty item coming back.
The option that avoids postage entirely
A partial refund. You keep the item, the seller refunds part of what you paid, nobody posts anything.
For a small flaw on something heavy this is better for both sides than paying postage twice. Can I get a partial refund?
There is also a return method where the buyer keeps the item and is refunded anyway, which sellers use for low-value things where return postage costs more than the item.
How the item travels back
Four ways, and the seller picks: you post it to their return address and add the tracking, they or their courier collect it, you drop it off, or you keep it.
If you are posting it back, get a tracking number and keep the receipt. A return that cannot be shown to have arrived is the one case that reliably turns into an argument.
The rule nothing overrides
A faulty, damaged, wrong or misdescribed item is returnable for 7 days, whatever your returns policy says. No wording a seller writes changes that — not "sold as seen", not "no returns accepted".
If you disagree about whose fault it is
Say why, on the order, with a photo. The seller has 48 hours to answer a return before you can ask Metzee to step in, so a disagreement does not stall indefinitely.
More: how returns work, how refunds work, how to set a return policy.