The marshall needed to know your banking information so that she could levy upon your bank account. That is a clever way she chose to find out. Simply ask you to voluntarily make a payment.
Once you did that, she will now be able to go back to the bank, levy upon your account, and obtain all the funds in your account.
Withdraw all the funds from your account NOW, and put them in another bank. It is probably too late, but it wouldn't hurt to try.
Yes, serving the writ will allow the judgment to be extended.
Please be aware that I may not be licensed to practice law in your jurisdiction, and therefore am not giving you "legal advice". You understand that an attorney/client relationship is not to be established.