No Cable Service for 10 Days, Run around, no help from Xfinity

I've spent 5 hour hours on the phone with Xfinity over the last 10 days trying to get my cable tv to work.  I have Xfinity service.  The first person did all the diagnostics, etc. and prounounced my cable box 'bad'.  Said they would deliver a new box Friday.  Never showed up.  Called again, same hour long conversation, repeated everything, she did all the diagnostics, prounounced my cable box "bad".  Said new box would be delivered Monday.  Never showed up.  Called Tuesday, third person, repeated everything, said a Comcast human being would deliver box Tuesday afternoon or Wednesday morning.  An hour ago UPS drops the box package at my door.  I plug everything in, follow all directions.  Same blue screen NO SIGNAL.  Everything is connected properly. 

I am at my wits end.  I have never experienced this before with Xfinity/Comcast.  They have always come through and fixed things right away.  It's been 10 days.  Nothing.  I have another "callback" scheduled with them now.  I am sure I will go through everything all over again and nothing will be fixed.  I don't know what to do anymore.  Does anyone have any advice or how to get help?

Thank you so much.