One of our projects there is a South and North building- The South is completely done but now they are stating we wont be paid the retention until the North building is done.
It's not 100% clear what your issue is from the way the question and description are set up. Is the issue that you just want to know whether the GC/Owner can withhold retention right now? Is it that you've filed a lien and they bonded around it? If you can give a little more information, someone on here can probably give you an answer.
We have yet to file a lien, but if we do and the GC bonds around it, could we go after their bond to get paid our retention?
Yes. The bond functionally replaces the lien on the property as security for your payment.