Bought a product online and they gave my item to someone else

Last week i purchased a gift for my son for Christmas.

Before I could go collect it, i received an email saying thank you for collecting your item. I called immediate to explain that I did not collect my item and was told that they would phone the warehouse and find out who collected it.

I am yet to receive any information about this and am rather upset as I've paid money for something I haven't got and no one is willing to sort the problem out.