Noiw this is a real rip off: they changed their loyalty scheme, due to naughty customers pushing some new staff to put unlegit stamps on their cards. Under the new scheme a customer has to complete 9 1-hour sessions within 2 months at one particular branch (WE or SH) before he's eligible for a free session (old scheme there was no time limit, you could switch from one branch to another), or 18 half-hour session within the same period. The girl also said you have to revalidate your existing card within this week, otherwise your old stamps will be nullified