Billing & credit clarification after changing cable/internet plan

I'm looking for some clarification on changes to my bill after changing my plan. I've spoken with 3 different people via messages and phone, but am still unsure the correct changes were implemented when they were supposed to be. 

I contacted Xfinity through the website's chat assistant on the morning 2/12/24. I informed the representative that I wanted to cancel my tv cable plan that day, they walked me through a 20 minute process, asked me to confirm and it seemed as though it was all done. Fast forward 2 weeks later and I receive a bill in the mail that doesn't reflect any changes to my services or amount owed, it was at that time I turned on the television to then realize the cable was still in fact on.  So I messaged the chat assisant again, and explained to them what had happened. This time the process was a little different, as they emailed me a link to authorize the cancellation, I proceeded with it and this time the services were in fact disconnected. I inquired about receiving a credit for the prior two weeks, being as though I did speak to someone and attempt to cancel the services on 2/12/24. They told me they would put a note on account and someone on the "back end team" would apply a credit. Still not feeling entirely comfortable I got somebody on the phone a day or two later to make sure the credit would be applied. I didn't want to be rude with the representative but I could barely understand a word she said. I couldn't make out whether the credit she was applying to my account was actually the correct amount or not.

Fast forward to today, I've received another bill, that doesn't seem to reflect the correct amount I owe, so I'm looking for someone that can go over the account and the specific dates of cancellation with me and make me comfortable with what I'm paying/owed. 

I'm also trying to find out when I make a payment, am I paying for the upcoming month or am I paying for the month prior?

Thanks in advance