We are currently unable to take payments automatically via PayPal Billing Agreements. This is due to a recent update to our billing system, we use a third party module for PayPal Billing Agreements and are currently waiting for the module provider to release an update to fix the problem.
We expect this to be resolved in the next 1-2 weeks, however for this month, please complete your payment manually by going to the invoice and making your payment from there. You can still pay manually through PayPal and automatic payments will resume as soon as possible.
Thank you for your patience.