If you are on a monthly DD membership then Phoenix Gym in Norwich reserves the right to change the price if necessary, although this is very rear and unlikely.
Members would be given at least 4 weeks written notice in the unlikely event this ever happened, although generally, any price increases would be for new members only and those members would know the new price of the membership from sign up.
If you are on a pay in advance membership then prices are set for that period of time but may change in the future on renewal.