Complaint about Flexi Club

I'm a member of first group flexi Club, last year April I changed my banking details and I notified them of my change in banking details. And in 2 months time (May 2018), I realized that they were not debiting from my new account, then I called, to make arrangements for three debut orders (April, May & June) to be debited from my account, of which they did and then they started debiting every month from then. To my surprise, on September last when I tried to apply for credit , I was notified that flexi club has taken me to ITC because they claimed I had arrears on my account since April 2018. Then I called, produced proof of payments. Then they promised to update my account. Even today, they haven't updated my account, when I try to make follow ups (which I did month after month), it seems no-one is willing to help, every consultant is passing me on to the next one, they're irritable with me, they promise to call me back when they do they can't explain to me why my account is still on arrears.