So, I'll take a stab at it but if anyone else has some input, please feel free to chime in.

I would start out by giving a donation to cover the minimum, but have cash in my pocket to make up the difference if you pass her standards.

After the first envelope is tendered and the clothes are off, you can then speak more freely, and if she is game you can let her know you have the difference in your pants pocket and can go over and get it.

This is standard procedure when extra time is requested and granted, so it should be fine for upgrading services.

Normally, YMMV is a factor for greek, as the gal wants to see what you're packing, so to speak.

I can't say I'd do any differently if it were my bum on the line.

Looking at meeting a lady and her website indicates that various levels of sessions have different donations associated with them.

The website also indicates that her willingness to offer the higher levels is a YMMV situation.  

So, here is the scenario I am curious about.  I request the "upgrade" option and prepare the donation appropriately.

After arrival, she decides that today, or for me, the "upgrade" is not available.  If determined in advance, a different donation would have been appropriate.  But now, this is after the envelope has dropped.

What is the expected ettiquette?  

Discussing this during seems like it could approach that third rail of fee/service.

Its basically her way to upsell and then not deliver.

Find a provider with an all inclusive rate for what she does offer.  Read her reviews (if you don't have VIP buy it) then you will know what services are usually on the menu and can expect.

Yes YMMV always applies

A provider can run her business anyway she wants. I prefer the pre fix menu, but if I was just absolutely dying to see her, I guess mrf"s suggestion is the way to go.

There are many things that run through your mind prior to a session. What donation to place down in return for the services you desire should not be one of them. Rate structures that are confusing, like the scenario you outlined, are simply not good business practices. As a "buyer of services", you should know what you are getting when you walk into the session and the cost to acquire.

As the others alluded to, unless this lady is someone you absolutely must see, its not worth the added stress level prior to the appointment. Questions of "will she or won't she" upgrade my services should not be on your mind. There are so many quality ladies who make it easy. You know what donation to pay and what services you will get.

Of course, your situation was a blatant upsell and rip off, but many girls will flat out tell you they can't determine the fs aspect until you've met. They don't make you pay them for a service you won't get, in other words. I am that way with greek. If a guy is not seriously small, it's not happening, but I tell them this beforehand, and don't take the money.

I have an additional rate for greek & its not something I can always provide given my clients blessings or curse below the belt. Say something about the envelope before you leave, any respectable provider will make corrections without hesitation. Now if she has 3-4 different rate structures without much explanation I honestly wouldn't bother, as that can be tricky and is a way for an unscrupulous provider to get you to pay more upfront not knowing that levels 2-4 area all the same services but, just fancier titles.

On the one hand, great news, I get to experience greek with London. Yes!

On the other hand, it means "I'm seriously small"

Oh, the trade offs in life....

Literally. EOM

I'm surprised that you would consider seeing someone who offered this kind of one-sided deal.

Unless she had a slew of reviews that said she was honest and fair, I wouldn't see someone who said "maybe I'll do this, and maybe I won't".

The Greek issue is understandable. It's also understandable that a woman won't want to kiss someone with foul smelling breath, or provide uncovered oral to a stinky dick.

But if I can't show up freshly showered, chewing mint gum, with my average-sized dick and expect to be offered a single prix fixe menu, then I am not going in the first place.

I really prefer to know exactly what I can expect to happen when she and I are alone.  If I want an upgrade, say Greek, I will make the arrangement ahead of time.  I don't like carrying extra cash to a date for possibilities, esp if I have never seen her before.

Swim

sure thing with a well-reviewed provider.

If your size dictates that she can't perform Greek, she won;t know that until you are there and she gets a gander at your junk.