I am receiving a “PEC-SUB-0002” error on multiple laptops. Do not have a VPN, and have never had another account. I’ve submitted three support tickets and wondering how long it takes for them to get back to you. Thanks.
Dear Samatha
Welcome to the forum 
That error occurs when Prolific has flagged the IP address that you are using for suspicious behaviour apparently
That can occur when you are using a dynamic IP that is also used by someone who does suspicious things.
Participants may be asked to use a different IP address (or provider) but I feel sure that they will allow-list the IP in the case of researchers.
Support times vary with the issue, but as far as I know there is no quicker way of contacting Prolific. E.g. if you respond on their twitter feed, they direct you to support. I hope that they have already responded.
In the meantime you may wish to you use your phone (e.g. by turning on tethering) or a different provider (net cafe? workplace ? home?).
I am sorry I am unable to help.
m(._.)m
Tim