Canceling Service

We have been trying to cancel service on mobile hotspot for 2 months. We don't have our passcode and cannot change it despite their instructions as to how to do it. My husband changed it online while talking to a "customer service" rep, but apparently it didn't "take". Of course. I changed our security questions twice, but of course, it didn't "take". Their website (Edited per community guidelines) and so does their customer service. Does anyone know how to change a passcode?