To edit/change your location please go to Profile Details here
Under Location Details, click on "Edit Location here"
You will then be taken to the page below where you will be able to edit/change your location details.
You can save your location details once for free. For any further updates to your location, there will be a charge of 4.99 GBP per update and can be paid only using a credit/debit card. (If you ever changed your location in the past, you are no longer eligible for a free location change)
The charge is the same if you change one or more fields.