If you have previously unsubscribed, you can easily reactivate your account yourself.

First you need to try log in with your correct credentials (you may need to reset your password first if you can no longer remember it). When you have entered the correct credentials, it still won't log you in, but instead a new option will appear at the bottom of the log in page. Click on the link that says 'Reactivate your account' and it will take you to a new page to reactivate your account.

If you pay for your membership, you will need to set up a new direct debit agreement and your first payment will be taken as part of the reactivation.