Indeed in Ireland I need to take returns to the post office. I also had a return that got lost in the post (wrong Tefal Actifry basket), resulting in Amazon charging me for the item again. However, after a few minutes onto their telephone support, they refunded it again.
One issue I run into regularly with Amazon is geographic restrictions even with their products.
Just like how there's VPNs for getting around streaming service geographic restrictions, several couriers in Ireland do the same for actual packages and indeed this works well for buying goods that don't ship outside the UK.
However, in this instance, the returns process can be a pain as Amazon provides a prepaid UK shipping label for items sent to the UK address, which don't work in Ireland.
Interestingly, Amazon has no problem promoting and selling its Prime service to Irish customers, yet the only way to use Prime here is with a courier's virtual UK address for deliveries (Amazon Prime does not ship to Ireland) and a VPN to access its streaming content.