DEBTING ACCOUNT WHEN THEY WANT

Please assist am very disappointed about the service that am getting from this company. we agreed on the set collection date which is the 25th of every month. But not they disregard the agreement and collect on the 13 or when they want to access my account. I tried several time to call them and as soon as explain the situation to the agent they just apologize and disconnect the call. I got I call from one agent this morning and she did the same when I was busy explaining she disconnects the call. I would to cancel my contract with this people with immediate effect and don't want to associate with such unprofessional business.