Bill doubled with no notice, promised credit never applied

I've been an Xfinity customer for years. My bill was $70.90. This month it's $130.90. Nobody told me. No email, no text, nothing. I only found out because I happened to log into my account and saw the number.

I live in a small apartment. I never needed 2 Gig and never asked for it. I was fine paying a fair price for normal service.

On Sept 15 an agent offered me a one time $60 courtesy credit and opened ticket ECM0025287857. It was never applied. Today I was told chat can't apply it and the ticket will just be closed.

Also today I got moved to 300 Mbps for $70.90. Meanwhile your own website right now offers new customers the same 300 Mbps for $45 with a 5 year price lock, and 1 Gig for $70. So someone who walks in off the street pays less for more than I do after years of paying you every month. I asked several times how long my price is locked. In chat I was told it's fixed. The order I signed says regular rates apply after the promo ends. Those can't both be true.

One more thing. English isn't my first language. That's part of why I never fully understood what was being changed on my account during earlier support calls. It shouldn't mean I end up paying double.

What I'm asking for isn't more than what was already offered to me:

1. Apply the $60 credit from ticket ECM0025287857.
2. Give me the same 300 Mbps at $45 with the 5 year price guarantee you're advertising publicly, in writing.
3. Tell me what autopay will actually charge on Sept 25.

If none of that is possible, I'll cancel and return the equipment. I'd rather stay. I just don't want to pay double for being a long time customer.