Or with a higher price, actually, if you want to, as “deliver today” isn’t 24-hour delivery but same-day delivery, so it might well be more expensive - if you are able to do it in the first place (do you have something like “Contact me if you need other delivery times than the gigs include” in your gig description?)
If it ends with a cancellation, you can try to appeal to support, but your chances probably would be higher if you sent the customer an extra to pay the additional fee, since their motto is “work it out with the buyer”. Not sure if they’d help with your OCR if you didn’t “give the customer the chance to pay the additional fee” first (from their perspective, it’s probably in dubio pro reo, the customer might not have noticed the option for 24-hour delivery, or that they could have contacted you to ask about same-day delivery, etc.). It’s improbable with how they acted but not impossible that they’d accept your extra, and the cancellation would be avoidable then.
It’s unfortunate that support takes so long to respond at the moment; as he didn’t order the 24-hour extra, you might have enough time to ask support to cancel vs cancelling yourself before the deadline, but if not, that’s an additional issue because it wouldn’t just affect your order completion rate but also your delivered on time rate then.