MONTHLY Zoom Webinar Subscription Cancellation

Our company currently has MONTHLY Zoom Webinars subscription that we get invoiced for and pay on a monthly basis but are being told that we are locked into an annual contract that coincides with our Zoom One Business Licenses.  We need to cancel the MONTHLY Zoom Webinars subscription as it is no longer in use and were told by our previous account manager that since it is MONTHLY we could cancel at any time.  There is nothing in the terms that states we cannot cancel before the next month's bill.  Please assist in cancelling this subscription and escalate to the highest level if needed.  Thank you.