They can't cancel their own system

One of their consultants did a shop online which I cannot access I've talking to their management company requesting them to cancel their service cause I didn't get what I needed and they keep on sending different links that I cannot login too to cancel I've never dealt with such unprofessional people in my life all I need is to cancel I no longer want to do business with this company and I don't wish other clients have to go through what I am going through don't do business with this company