Sent to collections over a disputed ETF that I already paid

I cancelled my service within 30 days. The contract states that an ETF would not be charged. My service was installed on 06/22/23 and I called to cancel on 07/22/23. They set the cutoff date for a day after and charged me an ETF. When I called I was assured by one rep that it would be removed, and another that I would receive a phone call. I never received a call back and instead received a bill on the 2nd of October. I paid the bill today and filed a complaint with the BBB to argue for a refund. It turns out they sent me to collections, but still took my money through the Xfinity website. This fee should not have been charged let alone affect my credit report. I have never in my life worked with a company that is so hard to get a hold of and cares so little about the customers that keep it in business. I need assurances from someone that this is not going to affect my credit report at the very least.