That's not racism. That's not a bigotted remark. I think he's calling you stupid. Sort of like I already told you I sent it once, don't you understand or don't you speak English? It's not nice no, but eBay's not going to do anything about it. Nada.
I personally wouldn't address that aspect with them. It'll only lead to further arguments. I would only deal with the transactional aspect and ignore the stupid/ignorant comment. I would explain that payments coming from the US can take 1 - 2 weeks to arrive and you'll let him know when it does arrive. I also wouldn't have said email by this date or I'll do this.
I would have just asked for them to tell you when payment was mailed and on my own, if I didn't get it by X then file the UPI. I don't warn them I'm going to, I just do it. For someone who may not speak English well or read your intent, the words alone can come across like a threat. Which then sets things off on the wrong foot.
