Glad the buyer agreed to repurchase - and hopefully the refunding has been straightforward for you both.

If the buyer paid for all three items at the same time, the postage should have automatically combined - but perhaps it was because they were sold via 'best offers', that the postage could not be combined?

Unfortunately, the way Simple Delivery works, means it is no longer possible to just refund some postage to the buyer after they have purchased multiple items - but not all buyers are aware of this, and expect the seller to be able to adjust the postage afterwards, without any trouble!

Out of interest, I wondered why some of your similar size/weight items have an Evri postage price of £2.94, and some have the Royal Mail postage price of £3.38?