Atrocious Service & Disgusting staff attitude

I bought an item at Mr Price in Bedford Centre where I normally shop.

However I lost my slip & don't want the item anymore, I also don't want to exchange it because there is nothing I currently want & they told me I cannot get a refund because they don't know the price, needless to say that the Tag is still on the item with the price on it & they can see that the condition is still new because it hasn't been used.

I need to know if it's even legal for them to refuse to refund me as the transaction should surely appear on their system. I am a regular customer asking for a refund for the first time & this is how they treat me.

Please can you assist me.

Angilque ***