Worst customer service

I was a customer for 18 years. Since the change my bill went from $50 a month for a single line to a $110. It was finally too much and I called to ask what I needed to pay to cancel my account and switch service. I was told when my final bill would be and when my service would end and I found a new carrier and planned my move accordingly. About 5 months later I got a call from a bill collector. They said I owed tmobile money I called customer service. I was bounced back and forth and placed on hold for over 4 hours. Finally I agreed to pay for an extra month. They told me the person who originally told me what I needed to do to cancel was wrong and now I owe an extra 97 dollars for a month of service after I had my number transferred out. I begrudgingly paid it and filed a report with their fraud department for being told one thing and being charged for another. A month and a half later I got a notification my credit score dropped 20 points. I checked my credit report and called the number for the bill collector. When I told him I had already paid t mobile he SCREAMED at me. Treated me like the scum of the earth, like some degenerate who doesn't pay his bills. I called tmobile again and they said I owed another 40 dollars now for a collection fee. I asked what happened to my fraud report and they said it was still under investigation. I offered to pay the lady more just to leave me alone but I was assured FOR THE THIRD TIME that after this I would not owe anymore money. So in summary they scammed me, they stole from me and even though I gave them all the money they demanded, they dinged my credit report. After being a loyal customer for 18 years...