Charged for modem after drop off at UPS

[RideAMustang]

I have had a very disappointing experience with the 5G /LTE Home Internet. I was approached by a salesman offering me a free 30-Day trial of this internet service that was newly made available in my area. I decided to try it, since I thought I had nothing to loose. Verizon is supposed to be a reputable company so I was confident that I would have no issues. I signed up for the service on Apr. 22, a few days later I received the modem and set up the service. After a few days I realized that the service wasn't on par with my current service and decided that it wasn't for me. I cancelled the service by May 15, which is within the 30 day trial. On May 20, I received an email for a last bill of $44.00. Since the account was closed, I was unable to look at the bill to see what the charge was for. I had auto pay set up and it was paid on Jun 8. I didn't pay much attention to it at the time because I thought maybe I cancelled late. On May 25, I returned the modem to my local UPS store. I threw my receipt with the tracking number on my passenger seat in my car (BIG mistake). I cleaned my car shortly after, loosing the receipt. I thought that would be the end of it. Unfortunately for me, it wasn't. On Jun 19, I received another email with a bill for $214. I missed this email at the time. On Jul 9, I was charged the $214 due to the auto pay. This over drafted my account and was charged by my bank $35. This happened right before my cruise and was pretty upsetting. I called customer service on Jul 9 to resolve the issue. Come to find out that the modem was never received. They tried looking for it in the system to no avail. I was told to go to the UPS store to get the tracking number and I was told they would call back the next day. On Jul 10, I went to the UPS store and was told that because the return label was NOT generated in the store but by Verizon, they couldn't look up the tracking number. The rep I spoke to the previous day did call me back on Jul 10. They submitted a fee return ticket on my behalf and said they would call later that day or the following morning. I didn't receive a follow up call. I waited until Jul 26 and called the customer service again. Still no sign of the modem. Two whole months after dropping it off at UPS, and nothing. The rep this time escalated the ticket and promised to call back on Jul 31, but no call was received. And so here I am feeling frustrated and at my wits end. It was supposed to be a free trial and now I'm out all together $293. I'm also getting nowhere on the phone. I'm not sure where to go from here. Like I said at the beginning, I am very disappointed  at how all this turned out and the lack of progress in resolving the issue. Hopefully, this will help someone else going thru this.