Guidelines 4/2018 on the accreditation of certification bodies under Article 43 of GDPR
Paragraph 9.3.3 Management of complaint handling
A complaint handling shall be established as an integral part of the management system, which shall in particular implement the requirements of points 126.96.36.199 lit. c), 188.8.131.52 lit. j), 4.6 lit. d) and 7.13 ISO/IEC 17065/2012.
Relevant complaint and objections should be shared with the competent supervisory authority.