What happens after 20 days and they want a refund in bitcoin? If bitcoin has gone higher or lower during that time, how do you figure out the refund amount?
The same thing applies to Steam.
You can pay on Steam with Bitcoin but if you are asking for a refund they will just give you a credit voucher for the exact amount you have paid.
To make an example:
You buy a game on Steam with Bitcoin and pay 0.01
BTC for it. This equals at the moment around 36$.
Now you are asking for a refund and than they will give you a voucher for 36$ and keep your
BTC.
Maybe you can use the same method?