The first thing you need to do is to log onto your email account and check to see if there are any forwarding email addresses set up.
You do that by checking in the settings found by clicking on your user name at the right hand side then click on "Mail" in the left hand column then click on "Auto Forward" and check.
If there are any addresses set up delete them
You should also check if there are any "Rules" set up. If a Rule has been set up you should have got a notification every time you log onto your account. This will also happen if you delete or change any Rules.
You then need to change your email password. If you use the email address on more than one device don't forget to change the password on them to your new password.
You should also contact your bank and advise them what has happened. Their security will be open 24 hours and the phone number will be on the back of your bank card.
I would then go through every web site that you log onto and change the password of every one of them.
I would also advise your contacts that you have been hacked and that they should be wary of any emails purporting to be from you particularly if the contain links or ask for personal information.
You should also do a full virus scan and malware scan of your computer. ADWCleaner is a free malware checker from Malwarebytes that you can download and run and it should find anything that should not be there
See the following link and sub links for more information.
How can I tell if my email account is no longer secure? | BT Help
