We have found that most companies hold the retainage for a year as by that time all QA issues have been (hopefully) checked, resolved etc in the event of back charges. Dan has always got his retainage back after that time. In one instance he did go to small claims court but he normally doesn't have that happen. Send an invoice for the retainage you're owed and see what happens. Good luck.
This is CABL.com posting #144478. Tiny Link: cabl.co/mLKs