Nu Metro double payment horror

I had the most horrible experience with numetro. I was double charged. When I called they told me they aren't refund specialist and I should wait for 7 days and provide bank statement showing the deduction. I done so then it wasn't sufficient as they required an actually bank from the bank with the stamp. I provided this and they mentioned that they were only able to pick up 1 payment and are escalating it to IT. 17 Emails back and forth I got a response to say that I cannot be refunded as they only see 1 payment and I have to visit my bank again. A month later still no refund, the bank cannot dispute as the funds has already been approved and paid to nu metro. I am still waiting for a refund. They aware that they can see two deductions on my bank statement but they can only pick up 1. I don't understand how that is my problem, because I paid for a service I did not use.