How do I cancel the Australian?

Can someone please help me I’m in the US and I need to cancel. I called the direct line that begins with 61 and I even did 011 in front of it. Nothing is working. I even used my husband’s phone who has overseas calling through work. This is ridiculous that I can only cancel by calling, but can somebody PLEASE help me figure out how to make this number work from the US? +61882062018