Who can I send an email to regarding customer service?

customer service is atrocious. I was put on hold for 2.5 hours to speak to a supervisor and eventually had to disconnect the line because clearly nobody was every going to come on. Normally reps have the decency to call you back or wait with you. I am paying $130 a month for 4 years for 1.2GB of speed and I am getting 75 MB/S as of right now. I have replaced Xfinity modems, made multiple calls to customer service and there's been service agents that have come over. They made me buy Xfi pods which were a complete waste of money. I work from home and it's critical for me to not have service interruptions during business hours that's why I have the best plan that Xfinity offers. My Internet service works but at night or very early morning is when I experience service interruptions and lower speeds. I have never got more than 600MBS even hard wired to the router.