[Closed] Kindle Fire HD issues purchasing apps etc from Amazon

Live in Rep. Of Ireland and a colleague has a kindle fire HD. It's registered with amazon.com. When he tries to purchase apps from amazon.com it tells him to go to his local amazon store to purchase apps. He goes to amazon.co.uk and it then tells him that the kindle is registered to amazon.com and can't complete the purchase. I think he's tried to de register it and the register on .co.uk but it picks up the IP address and doesn't allow it.

Does anyone know of a solution?
Should the amazon site he uses be the EU site? Even though the site looks as though it for Germany, France, Italy & Spain only!?

The last email he got from customer services said send it back for a full refund which isn't exactly helpful!