(Obligatory long post warning).
Background
I mostly make logos with custom fonts.
Some time ago I had the first order with this specific buyer which went fine, he approached me politely and while he was a little bit nit-picky and brusque when it came to corrections, I gave him the benefit of the doubt regarding his tone as he said he had to machine translate some fairly complicated words and sentences in English. He was ultimately happy with the end result, and that’s it.
Recently he came to me again for another logo design for a project he’s working on and now it’s gone downhill.
So, about him…
The first proper red flag was that he placed the order while we were discussing how I would’ve approached it. I initially wanted to refuse it as it was something for a third party, but I went on because the owner was fine with the sketch that he made.
Still, let me at least make a custom order first for convenience or something since we were discussing for some extra time to be allotted? What happens if you’re not there when I ask to extend the delivery time or stop replying? Come on.
Of course I’ve had people make orders on a whim, but all of them filled in their requirements immediately with proper detail and had expectations within the packages’ contents – just stating to make clear that this isn’t a "please message me before ordering” problem, like it or not that’s how Fiverr works, it’s an accountability problem on his side as he hasn’t done much/done it properly.
I should’ve been more confrontational about this and it’s a lesser thing, I know, but it’s kinda hard to not let it slide with orders on here, seller’s stats wise.
This said, he more precisely wanted to have me work on an original font for said sketched logo, and while we initially proceeded on something based on a font I suggested that he liked, he then abruptly shifted the focus from upgrading the logo with an original font… to using another free one he likes, with just one custom letter serving as an identifying mark.
He simply took over every aspect the direction of the logo and now he doesn’t want me to do anything but “improve” this letter in his rough sketch (read: follow vague instructions verbatim and change the basis of it when he wants to), as if looks final.
It’s become more orders than requirements, and I don’t understand where he’s getting at all with this. A 180° turn where I’m not allowed to know or have a say in where we’re heading.
The cycle so far has been, “do this” 
I do it like he wants it He doesn’t like it and I’m apparently “making it hard” because what I did isn’t like he asked (but it is) Onto the next idea/sketch/order of his and how to handle it.
He’s been complaining various times today and he just dropped multiple, subtle ad hominem-y stuff and passive-aggressive jabs at me, so at this point it’s obvious that he’s just being mean. Right now I’m following what he says (If I can…) and it’s coming out pretty appalling.
I don’t know what to say. I am doing my job as usual, and it has always went well with others, nobody reacted weirdly like this so far.
Anyways, this has been really stressful and he’s upset me a lot, despite all of this happening very quickly.
I’m afraid that by now this job will end in a bad review/a cancellation/declination of delivery extension/etc., basically just about every negative outcome.
I’ve had stellar feedback on my page and lots of tips so far. It would be pretty frustrating to end up like this right now, and I while was aware something like this was going to happen sooner or later, it’s particularly bothersome as I’m close to levelling up.
The lack of possibility to block a buyer account silently without reporting, the existence of chargebacks, post-completion cancelling shenanigans and so on all worry me. Don’t know if CS could even side with me unless it was to go really sour since he has been trying to keep his cool while berating me. 
How do I even approach this? I just want to make sure he can never order from me again regardless of the outcome, with minimal harm to my profile. Got a strong gut feeling from this turn of events and I don’t want to see this person becoming vindictive.
I haven’t been breaking any ToS, am delivering my service as advertised and everything else, by the way.
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