The refund is probably not worth the time spent building the case but it sends a valuable message. Keep your promises.
I would be surprised if Asus even sends a lawyer to defend against small claims. Might be better to form a class action.
If this went down the small claims track in the UK then ASUS wouldn’t bother with a lawyer because you’re not allowed to reclaim legal costs in the small claims court. So unless ASUS thinks they’re gonna see a flood of similar claims happening, then the cost of a lawyer would probably be triple the cost of settling, or even winning the case.
Also class action cases are very rare in the UK. In the past the courts have generally refused to approve class action cases. It not like in the U.S. where there’s a cottage industry around class action cases. I’ve personally never heard of a class action case happening in the UK, I know they do happen, but they’re so rare that they don’t make it into the news, and most people will never involved in one either directly or indirectly.