They're not advertising full service, just watching them and "cleaning up".
Q. Do you do extras? A. Yes but this would be an additional price
Q. What are the extras? A. We allow oral (Blow job, licking, rimming, fingering, sucking)
Q. How much are the extras? A. Please contact us and we will tell you the extra price for these
There's a recent FR on AW indicating that "BJ, CIM, Cunnilingus" was £50 extra.
No experience here, it's not my thing but how the pointer to the FR helps.