contact for microsoft 365 subscription

After upgrade to Catalina, MS Office apps no longer working. Forced to get trial of MS365 and today I was charged for an ANNUAL subscription that I expected would be MONTHLY. I don't want to pay for a whole year. In fact, upset that I have to purchase since I already owned MS Office. How can I change or cancel AND is it possible to run my previously-purchase MS Office apps on Catalina?