Any councillor can make a complaint. In the first instance your PC should have a complaints procedure policy. If so follow this. If the complaint is not dealt with by this method then you can use the MO pathway but they will only investigate and rule on code of conduct issues. It may well be that you feel that the code has been breached. What you need to do is to be able to provide hard evidence to the MO of the breach ( documents, minutes, statements, emails etc. etc.) because hearsay or gossip carried no weight with the MO. SO- gather as much material evidence to prove the complaint and be prepared to stand by your principles even in the face of criticism from some quarters around you.