I feel for you dude, that post rs error is serious and they treat you like junk I'm 20 yrs in and am receiving the same treatment as is my parents and 2 of my friends who have cases/issues being ignored. They don't care about us anymore so I don't care about taking them to court for there terrible out of date equipment. You are right they are blagging us all with the network in places barely holding together with the over sold services with a network that can't cope.
Wish I had some answers how to fix but only engineer/networks can, I see your downstream is centered on a few channels and others +7db someone more qualified than me can tell you about tilt etc I'm merely a struggling customer too, what I do know is post rs errors in those numbers not good at all, good luck.
Regards