After 15 years of decent internet, what happened in the past 60 days?

I have been a Comcast customer for over 15 years, or as Xfinity labels it, I am a "diamond" customer.  I have pretty much had the same service for that entire period of time, and while I have thought it was on the expensive side, I kept it primarily due to the internet.  Without notice, at about the end of May or first of June, my internet signal degraded.  Nothing wrong with any of my connections or my modem, and the $265.00 a month payment didn't change either.  Here's the rub, and it is a burning rub as well.  Xfinity reached out mid June and offered to upgrade my internet speed (to what it was for the previous 7 years) for an additional charge!  Are you kidding me?  You degrade my signal and then offer to return it for an additional charge?  That should be illegal, and at the very least that just stinks really bad.  This is a perfect example why people hate Comcast.  And you wonder why you are losing so many customers...this is the reason why.

If anyone has the nerve to respond to this post, please don't ask if all my cables are tight.  All of the basic things have been checked.  You degraded my signal...look there.