How can I request a duplicate receipt from an Apple Retail Store?

Hello everyone,

I was wondering if anyone knows how I can get a duplicate receipt from a purchase I made at an Apple Retail Store (Convent Garden, UK).

Tried all means of contacting Apple but nothing seemed to offer an option for general questions and requests without making a more severe repair request and it doesn't seem that I can contact the store directly. And I'm in Portugal so going there is unfortunately not an option.

Thank you in advance,

Nuno