refuse to give my money back

Really upset with the services we got from montana branch. I bought a drone for my husband in december and it was broken, took it back, and they told is they dont have more stock, gave us a voucher to use. Today i went back to find out if thry got any swing***** as there is nothing else we can buy or need to buy. We asked if we can have our money back. The refuse. What a waste.This is so unfair towards a customer. Pour customer services and what a waste of money and time and petrol! But thanks for not helping me as a customer! Ive spend 650 at the store and they refuse to help me.