The commission may deal with a complaint as a representative complaint if the commission believes, on reasonable grounds, that—
(a) the complainant is a member of a class of people the members of which have, or are reasonably likely to have, complaints against a single person or group; and
(b) the material facts of the complainant's complaint are the same as, or similar or related to, the material facts of the complaints of other members of the class; and
(c) common questions of law or fact arise, or would arise, in the consideration of complaints that have been, or could be, made by other members of the class in relation to the complaints; and
(d) it is desirable to deal with the complaint as a representative complaint.