IDEA: Never stop QC from halting questionable production: a good example of your commitment to customers.
You must allow your quality control department to do its job. They should have the power to stop production and restrict shipments on faulty or failed production. It is costly but will save face with customers in the long run as well as protect your reputation. Tell them to scream as loud as possible in order to stop production, investigate and solve the problems and then get good quality production back on track.