I got a reply from the clinic very soon after I got in touch with them. The initial appointment had to be cancelled by the clinic and I re-booked. When I attended, they gave me a trial session to try out the treatment and it was made very clear to me what I was paying for - length of session, which was an hour, amount of sessions etc.
When I attended the appointment they were trying out a new machine and I found that it didn't really work as well as the previous machine. When I said this to them they agreed, said other patients had said this and gave me a free session instead, which I was pleased with.
Overall I was very happy with my experience and would return here in future if necessary.