Different rates are common and it can get a little confusing at times.  Many providers will tailor their donations to the ad site their using.  BP might be one rate, Eros another.  There's a local review board near me, which I can't name because of TER rules, that has a reputation for having cheaper rates than TER, because of the guys who participate on that board.

When seeing an escort, at times I've paid the high rate and other times I've paid a current advertised lower rate, just depends on my mood.  If I pay the high rate I don't say anything, if I pay the low rate,  I might put the donation in a thank you card and reference the ad rate I paid.  Or sometimes as I'm leaving after the goodbye lfk, I'll mention something about the fact I paid  a rate found from a current ad site.

Remember the provider's site might have been up awhile and Christmas time can be slow for providers so the escort could have thrown up an ad with a lower rate and forgot that her site has a higher rate.  Good luck

I book an hour on Monday at 1 pm at your incall?  By indicating where you found her ad, she should be expecting that rate; besides, it might be a holiday special.  You can bring along the difference so that once you meet, and confirm the rate, you have the $ to make it right.

check with her to be sure it's current.  BUT be warned, pretty often low priced "Specials" is for Lesser times or services.  If you want the whole banana, don't be surprised if you want to opt for the regular rate & service.  It is hard because you can not discuss in advance.  It happened to me just once...  My fault because at the beginning of our session I did not make clear the time interval I wanted.  So when the initial time slot was ending, I asked to extend & fortunately she agreed.  
skb

Some new escort sites steal pics and profiles from ladies to populate their sites.  Many require the gent to join.  The problem is that, once they put up the info, they do not update it.  It simply stays there.  If the lady changes her donation, they do not change it.  In fact, often the lady has no idea they are on the site.  When they find out, these nefarious sites refuse to remove the profile.

Best to mention where you saw the ad when booking.

that have posted - there are many ways our rates can differ. Unfortunately, we can't always control what is out there and as previously mentioned our info is taken and put into sites that we may have never heard of. Also, some sites make it difficult to delete old ads.

Since I always book all appointments through e-mail, I ask the gentlement where they found my information and what type of visit they are interested in. This gives them the opportunity to say if they found some sort of special they would like to use.

Summer

I agree with the other ladies. A lot of the times  we have no idea  where the rate came from or it's from long ago. When your scheduling ( if she doesn't ask) let your provider know where you found her. I have run into this problem several times. Now if it is a first meeting I just add a little note of  my donation amounts in the confirmation email. Also  Keep in mind  if your wanting any "special" services ( meaning other than standard full service) there could be additional donation request.  If in doubt always ask before you get there
Good luck