Page 1 of cashier forgetting to pack coat

We purchased some childrens clothing items last sunday and only noticed last night that 1 of the 3 items (a small coat) was not packed when paying for the goods. What are my rights on claiming this back? I mean, you dont expect them to leave out items right? Btw, I called the store and they couldnt do anything as this wasnt logged by the operator. They told me to write to their customer services department. Does anyone know the terms & conditions? This is a xmas pressie so I dont really have the time!

Surely all checkouts are coverd by security cameras, and is not the checkout person`s name on the reiciept ( spelling wrong) along with time and date.

Oscar.

To be honest it`s xmas and I didn`t want to stress myself out.
Their headoffice were kind enough to take my word for it (even though the cashier said that it was the first item and thought she had put it in the bag) and refund me with the equiv. in vouchers.

Thanks anyway!