Worse service in history

I have a short term loan with Wonga, on the 30th of May I was debited twice instead of one debit. I’ve previously spoken and arranged with Wonga for one debit to be taken on the 31st of May and they took two debits. I’ve been phoning and sending emails and following up all week with regards to my refund and no one gets back to me, when I call I’m being told they have system issues and I called again today and was advised the lady that processes refunds is on sick leave and there’s only one person that can do this. This is unacceptable why am I paying for Wonga’s mistake? I want my money I cannot wait and I cannot accept their pathetic excuses. No one phones me back because I call with my airtime and no one cares to reimburse me. Please help me I need my money as soon as possible