extended service issues -- neighborhood over-subscribed

We experienced service issues for a period of approximately 9 months from January through September of this year.  The issue was finally resolved a couple of weeks ago.  Throughout this period we opened approximately 15 tickets and had 6 dispatches.  We were finally informed that the network in our neighborhood is over-subscribed and that they were aware of the issue and waiting to do construction.  This information was provided to us by a field technician and his supervisor.  The supervisor informed us that once the issue was resolved we could request a credit for the extended outage.  The reality of the situation was that the internet circuit would drop or become unresponsive dozens of times a day.  It was unusable and we had to subscribe to a backup circuit through a competitior.  The backup was much slower but reliable.

Comcast construction/repairs was finally completed a couple weeks back and things are working well again.  However, efforts to get credits for the extended outage have been stymied but customer service agents who simply cannot look at the big picture.  A $15 credit is laughable and insulting after spending $900 for a circuit that was completely unreliable.  Efforts to escalate to managers and open escalations go nowhere.

I am not asking for anything unreasonable.  I would just like a credit for the period of time in which the circuit was unusable.  This is a fair and reasonable request, especially since Comcast is aware and has recognized the issue.  How do I get in touch with someone that can look at the big picture and provide a reasonable resolution?