Poor client services

I have been trying to contact them, emailed them, with no success. I'm being trying now for 3 months to change my date of installement with no success. Last month I missed a payment, because of our salaries that were paid in later. I did a manual payment, but could not manage to get through to them so that they not put a double installement through. Can't get through to them. 2 people said they will call me back. Nobody called me back. They are ******** and aren't interested to help one