Noc from previous auditor

One client has been appointed a our firm as Tax Auditor as well as MVAT Auditor. Client had issued appointment letter in this regard. Our firm had communicated with previous auditor and obtained NOC from him for both Tax Audit and MVAT Audit. But now the client has hand over MVAT audit to same pravious auditor from whom NOC has been taken for Tax Audit and MVAT Audit. That auditor has completed the MVAT audit without communication or without obtaing NOC from us. The query is : -

1. Whether it amounts to professional misconduct under our ethics that that auditor completed MVAT audit without communicating with us or obtaining NOC from us?

2. If yes, then what is procedure to be followed for filing complaint and taking disciplinary action against such member?