Cancelling monthly subscription

Our company used ZOOM 100 Events for just one month. I sent a request to cancel the service, but no one from ZOOM responded. When we received an invoice, I reached out to ZOOM again to request cancellation. I received a notice that someone would get back to me. While I waited, I received another invoice. 

In September, I finally managed to reach a person at ZOOM named Maximo. He assured me that the service would be canceled. However, after waiting for a response, I again had to reach out to him by phone. During this call, he mistakenly thought I was trying to cancel our yearly subscription. After clarification, he said he needed to forward my request to another department, and that I would hear back from them.

Unfortunately, I did not hear from the renewals department (Cezar). When I eventually got in touch with Cezar, he said he needed to look into the matter. To prove that I had communicated with ZOOM, I had to take screenshots of our correspondence. We eventually received a prorated credit for October. 

I requested that ZOOM waive the outstanding invoices due to their delays and errors, but each time I inquired, I received an auto-response stating that I needed to pay the invoices, as if I had never spoken with anyone at ZOOM. Currently, I am on hold with ZOOM again for over 20 minutes because I received yet another email asking for payment, and the person I need to speak with is not answering his direct line.   I cannot get through to his manager, Chance Reeser.  1000% frustrated.

Although I was assured that the invoices would be waived and I sent a follow-up email to confirm our discussion, I am at my wit's end with the service I have received.