What I would do is call the company and ask to speak to their ISO 9000 management representative. That's the person responsible for the quality system. I would brief him or her on the chronic anti-customer events. I would ask them whether they have carried out documented corrective action on these problems. Many of the problems you cite are directly related to problems in their contract review process.
Suppliers can be de-certified, but it is rare.
As an escalation step, you could contact their ISO 9000 registration body and complain to them. I can help you find out who their registration body is if you'd tell me who the supplier is. One of the weaknesses in the whole ISO 9000 process is that the registration body auditing process is, in my view, not nearly rigorous enough. At the end of the day, how well ISO 9000 helps suppliers depends on how determined and committed their top management is. I'm not even sure if these questions are applicable or you understand them, but I thank you for your time.