Yes you have up until 48 hours of the start of your session to cancel and receive a credit. This is done on your online account. Go to the 'Summary' tab (previously called 'Bookings'), and to the right of the date you want to cancel click 'Cancel & Refund'. Please note that we do not refund sessions to your bank account but you will be given a credit note to use at a later date.
If you are cancelling within 48 hours of the start of you session then a refund will no longer be available and the only option will be 'Cancel'.
If you want to 'swap' a session, you will need to first cancel the session you no longer want, then with the credit issued rebook the new session. If the session you want to swap has missed the 48 hour cut off unfortunately you will not receive any credit for it so you will have to pay for the new session outright.
There is a tutorial on our >>BLOG<<.
Also see the FAQ: 'CAN I AMEND MY BOOKING?'