Unlimited plan with overage charges

I've chatted with agents in the past and gotten some of the overage charges resolved, I was assured I would not see future overage charges, but over the past many months I've been charged overages 5 out of 6 of those months. I have a statement from back in May or June where some of those charges were reversed, and I have a screenshot of my plan being described as including unlimited internet (which hilariously now that benefit is not shown when I compare my plan). All told I've been overcharged north of $300+ and am tired of getting the run around and have a number of local fiber providers knocking at my door with better pricing, plans and REAL no limit plans... I just want the $35/month plan I was promised with no limits and the 200mbps. Earlier this year Xfinity "upgraded" us to faster service apparently "for free", but considering my monthly bills, it sure feels like I've been paying for it.