Canadian Tire

I bought a Amazon tablet for my son for Christmas, I didn't realize you couldn't download stuff from Google Play. So I took it back not having my receipt. I had said that I didn't want the return to run out and asked if I can return it. So they said that they couldn't give me cash back and all they could do is give me a gift card. I hummed and hawed. Then they said if I'm to find my receipt they would take the gift card back and give me my money back. So I took the card and a few days later I found my receipt. So I took the receipt in and now they are not falling with what they had said they will do. I'm not impressed! So what is going to be done with this matter?