@emilyuk
It's more the ladies ( Lady in my case ) that say they do it for no extra charge and then it is not available even for extra.
As having only did it once ( which has got me wanting another go lol ) the girl in question had consumed my member up the rear without me hardly noticing so I don't think size was the issue with second lady, although advertised she just didn't provide the service at all, full stop.