@Home supervisor ZERO customer service knowledge

I took a gift back for a gift voucher to purchase at another store,the supervisor at Seapoint Cpt Mr Simphiwe returned the funds to the purchaser on her account, after almost 30min instore , all he could say was i will call customer service , not sure how long this will take though, since i was in a rush, i was told to take a pic of the return slip and he will call me, after 5 min i get a call to say he is sorry, its already returned to the purchaser, nothing can be done. I was totally mortified and humiliated, just to think what the person that bought this will think of me. How do i explain myself why the return was done, Mr Supervisor at Seapoint @Home, your body language and customer service as the go to person in-store was not even 1 star, I will never shop at your store ever, this was my most embarrassing moment to the purchaser