Mismanagement of Funds

I had returned an item via post office and Spree stipulates that you send them proof of payment for the cost of the packaging that you incur- which I did. However I am just worried in a sense that I had requested a store credit, which I received and as of yesterday made another purchase from the store with it , however I also received a refund of the same amount for the item via EFT. I do not want to be held accountable for this management of funds as I just wanted the cost that I incurred from packaging be sent via EFT and the item that I returned, the amount be converted into a store credit , please kindly look into this promptly.