Oh wow, thank you everyone for all the replies and advice!

The item was sent correctly to the address provided however it was a business address...so I guess they may have changed jobs or maybe reception didn't know who they were?

@curraone - I think I will contact the buyer first to gauge their attitude and ask them what they would like to do, and include a picture as you suggested.

@mbselections00 - Thanks for sharing your experiences! I wouldn't mind losing out on the postage as it's not a lot of money but it always easier to take a loss when your buyer is lovely 🙂

@beautbots01 - I will definitely send my messages through Ebay. I do agree that sellers shouldn't have to pay extra postage if the buyer is at fault but this is a unregistered letter with no tracking and you are correct in saying I cannot be sure the buyer will not react negatively.

@digital*ghost - Thank you for your advice! It never occurred to me that maybe the buyer might change their mind and put RTS on it...I hope your RTS situations goes well and I will get in contact with my buyer. Your policy of refunding the item price or asking for the postage sounds good so I may ask my buyer that too, thank you!

@lou - haha, yes, I am very happy I got it back. It is definitely a step up from it being lost. I will ask the buyer to confirm their details then see how it goes.