Worst experience ever

I need to file complaints on the techs that I've worked with the past few weeks. It's literally one after the other just telling me the same lies that they fixed my issue and are working on it only to find out from the next tech they did NOTHING. I have to explain the ENTIRE situation every time. They will assure me not to worry and they are the right person to assist me but it's ALWAYS the same. I sent my z fold 6 in like a month ago or so and they claimed they did not receive it and that I was going to lose my monthly credit for my z fold 7 I upgraded to AND be billed $1000 for my old device. They supplied the shipping label and refuse to allow me to track it.. Finally last week AFTER SIX HOURS running in those same circles with a new agent every ten or twenty minutes they finally got me convinced enough with another LIE that the issue had been resolved.. They had contacted assurance gave me a number and assured me they had located the device with assurant... I would not be billed for the rest of my old device and I would still receive my monthly credit.. LUCKILY I'm no newbie to xfinity customer service and their tricks and I logged in to check my account only to find that it looks like all they did is push it to the next month. I have a nearly $1000 bill coming out for the device they have and REFUSE to talk to me about it. All they have wanted to do was waste my time asking questions that I've answered countless times. I don't know what to do and I'm at my wits end. The next step I can think of is warning my bank of fraudulent charges coming around that time period to reject them. I NEVER would have upgraded if I had knows they were Going to pull this [Edited: "Language"].