They all do post this but it's mostly just on the surface, just as people do manage to cancel orders and get refunds from Bitmain, as you can see they agreed to send back the funds to the original wallet, so they agree on a refund but with their conditions.
Well that sucks, even if Bitmain is operating like that and I would never personally buy from such company. Why not mentioning that in TOS, that money can be refunded only to the address from where bitcoin is sent?
First because in the ToS sales are final, refunds are from the strat out of the equation normally.
As for the other thing, everyone is buying, because there are only a few manufacturers and because the retailers are way more expensive and you risk far more money with a scam, and most importantly, this is not a t-shirt that you order at 8 pm and at 8:05 you see a new pair of jeans and you think the t-shirt is no good anymore and you cancel the order. Most that deal with gear make their plans weeks in advance, they won't change their mind 3 hours after the purchase, this is the thing that triggered a lot of red flags in the OP story, even without the whole ledger thing.
And, look at that:
What if he used somebody else account and coins to pay?
At this point, if as stated above Cannan refunds the payment to the address in question and we see the funds moving (which should be impossible with a broken device) then OP is clearly lying.