Amazon complaint: Hard time returning a TV

I’m an Amazon Prime member and decided to buy a TV on Amazon Prime day. When we tried the TV, we didn’t like the resolution of the screen and it was too slow to load some videos, like when playing video games or on Netflix, so I requested a refund. They accepted the refund but when we took it to Canada post, Canada post wouldn’t accept it because it’s too big. I contacted Amazon and they basically told me that this is my problem now, and that I have to find a way to return it on my end with other carrier. We quoted some couriers and all of them wanted to charge $300 to return a $700 TV.
Amazon is always advertising about free shipping and returns, but when we buy on Prime day, and want to return it, they say that there’s no free return voucher for this item. What a way to back-fire a member appreciation day.
And what really bother me is that they sent a courier last month to collect a $24 night lamp but won’t do the same to a $700 TV.