It seems the basic tariff seems to be £50 and £100 for the basic 30 and 60 minute appointments. From my experience, I have had excellent appointments with North East agencies at this rate. As a result, there is an automatic reluctance to pay more - whilst £60 and £120 is only £10/£20 per appointment more, it is actually a mark up of 20%. Looking at this from the other point of view - wouldn't most people jump at the opportunity for a similar discount!
Given that there is a reasonable amount of choice at the lower figure, from my perspective, I have very little desire to pay more - and only rarely do I book in for an hour long appointment. Having said that, the reviews for Suzanna (OP) are very positive, and it is this kind of feedback that may eventually spur me to book - especially given her 'likes' that can be shared during an hour long appointment.
for the record, I haven't ever gotten round to booking Suzanna yet, as I know that if I book, it would have to be a 60 minute appointment!