Thanks for explaining that, shaf. Let me give you some advice to all of you to avoid this kind of situation in the future:
1) Do not deal with users privately only. Only use Marketplace posts to do your trades, sales, and purchases. This applies to both sellers and buyers. If we see publicly what happens, it's easier to assert if someone is being a shithead scammer or not.
2) as Raion-Fox says,
COMMUNICATION IS KEY! Everyone can have issues, we're not perfect, and I know I had them in the past myself, but you need to keep communicating. Not explaining and/or ignoring your buyer's questions and worries leads to problems. Transparency is fundamental.
As it was my initial feeling, I believe you did not act out of malice (I hope you did not act out of malice), and I ask you that, from now on, if you have services or items for sale, that you make a thread in Marketplace about it, and be transparently communicative throughout every transaction. You can apply the same practices to Amibay. I don't understand how the transaction between you two started, but it wasn't ideal, and it shouldn't happen again.
Advice for Acill (and all prospective buyers), is to never deal with users only in private like in this situation, and to leave negative feedback for shef in the
User Feedback thread, before resorting to more drastic real-life measures. I am afraid I am a little too late for that, but hopefully for the future, it will be advice well kept.
I hope this is the end of this situation, Acill, please report back if everything has been sorted!