We are a Texas millworking subcontractor (we work directly for the GC). We sent the required notice of retainage. We have received half of the retainage with the GC saying that they are holding the remainder (apparently it has already been paid by the owner) until July 15 - which is the 15th day of the 4th month since we were on site. 1) It's still important to file a lien since that's the only leverage I have, right? 2) Do I need to send another notice of retention with the revised amount before filing a lien?