Complaint and possibly peer to peer chat

I am looking for the peer to peer chat or a way to directly message with someone in customer service (preferably someone who speaks English fluently) sector so that I can submit a complaint and also discuss how I can reimbursed for overpayment the past 5 months. I looked in the forum at old posts on how to send the chat but the instructions don't match what I am seeing on my screen. Thank you!