As others have stated you would not be doing yourself any favors asking for a refund.  The provider has prepared for the trip to the Greek Islands.  It would be tacky and unfair to ask for a refund.  Plus you are risking other consequences to your reputation.

Of course not but I don't see how the two situations can be compared.  I see the surcharge for Greek as different because it's an add-on.  Does the advance preparation in and of itself warrant the surcharge?  Not sure but I tend to think the surcharge should be paid regardless in the interest of good manners....this we agree on.

Sorry, but I don't agree totally with your thinking about getting a refund.  Obviously the lady is preparing herself for this.  If he is aware from prior experience that size could be an issue and he's willing to take that risk.  She certain has the right to stop it if it's painful.  Same with any other activity.  

If it's a size/girth issue/provider not being ready for Greek/doesn't feel like Greek that day, it should be something that's readily obvious when she first sees the package or he first tries to stick it in. At that point, if she stops him, then I feel a refund is totally justified. It's not like he was pounding away for 3-4 min and then she said no no no it doesn't fit stop. Otherwise, it'd be a surcharge for "attempt at Greek", and any provider could slap an extra C-note charge to their rates and then go "nope not feeling it" and keep it.  

I can't imagine discussing prior to a first meeting.  You showed up expecting it without advance notice, I'd expect refusal.  If she's sized you up, you could get an agreement for a future date.   If it was prebooked, I'd include the amount in the donation on arrival.  If I were to tip, I'd leave it in plain view on her dresser or press it into her hand as we goodbye kiss.

I concur that if you agree that it's on the table ahead of time, then if you can't make it happen, the fee should still be expected. However, if it's YMMV and she tells you she has to make the determination on the day and she can't for one reason or another, then the upcharge better be refunded.  

Whether you get off or not is NOT on her, but on you. If you have decided to perform Greek and she allows it, you should add that to the envelop at the start of the session.

for whatever reason it's on her, if you're the reason it doesn't happen it's on you. If she gives you back the money and you accept it when was your fault you failed to complete the deed, thank her and leave her a nice tip.

And you should include any additional donations requested for additional services, as her website should say.  This should be in the envelope...

the decency and common sense of the person "doing it".

... Greek will bankrupt you!