Pathetic customer service

It's been more than a week, and I still cant get refunded the extra installment that Blue label connect has taken out of my account. All I get is call centre agents who call me and ask for my account details but do not have the account payments to check why there was an extra installment taken out off my account. What a waste off my time. Worst customer service I have ever received in my life. To date no senior management has called me to resolve this problem.