Hi,
Yes, it does seem a lot. I'm in a very affluent area and it's about half of that, on an on-going basis.
Around here you would easily pay £15/hr but only on an ad-hoc basis, not if you were committing to a regular slot. If paying £15 enables you to do a £50+ treatment then it could be money well spent, especially if you're not tied into anything.
Sounds like you probably need to look into it in a bit more detail and gain some clarification. If you feel they've completely mis-calculated how much they can charge it might be worth going back to them with a counter-offer. If they're new they might accept....