Don't get into the situation in the first place!
I try to sum up in the first minute or two whether the p4p can 'read me' and be sensitive and receptive to what I want without me being too directing OR can produce such an incredibly interesting scenario that I want to go along with it and see what happens OR hasn't got a clue.
The last of these is by far the most common.
In which case I will take control and just charmingly make sure that she always has something to do that I want her to do. It involves putting on an act but works most of the time. As our resident p4p said, suggest nicely but firmly. The thing is, you have to do it very quickly, within the first few minutes of the punt: Establish who's in charge.
There are times that I would really just prefer to 'go with the flow' but that only happens with one or two that have the emotional and sexual intelligence to interact as equal human beings (They often become a regular). I don't blame them if they can't: they're getting paid, they're shagged out, and a large proportion of suckers are so blown away that they just let her do her routine, whatever the fuck that is. No disrespect, p4ps aren't dogs (well, most aren't) but it is a bit like training a dog. Be gentle and firm and let her know who's in charge or she'll run all over you and you'll wonder why the fuck you are paying her.
There's the odd one (usually without much English) that hasn't got a clue and doggedly insists on what she believes is best, however sweetly one tries to guide. Try to tell her otherwise and she'll reply "most people enjoy it" (as if you should as well and it's your fault if you don't). They are simply pump, dump or walk.
Honestly if she suggests that you go down on her and it's not what you want, then she's not very bright (though it does mean you have also lost control). What she should do is politely enquire if you want to. A bit like "would you like a glass of wine?" A mere casual option. So, "Do you want to go down on me?" evinces the answer, "No, I'm fine just doing what I'm doing" / "enjoying what you're doing" / "No, what I'd really like is..." (If you don't know what you'd really like then do some quick mental homework ffs!)