Unfortunately, in this instance, you just have to suck it up. You bought from a Chinese seller with absolutely horrid feedback. You have zero chance of getting the return postage refunded. In future, open a dispute, don't just return an item. Given your seller was Chinese, highly unlikely they would pay for return postage, so they'd have no choice but to refund. As you didn't open a dispute, there is nothing you can do.
Probably a good thing you sent it back, it could easily have burnt your shed down. Don't buy carp like this from Chinese sellers. They are cheap knock offs and extremely dangerous.
