Faulty power bank and no refund

I have purchased power bank from askmebazaar.com and i received faulty power bank immediately i call them up and they told it will be get collected soon and you will get refund , they also took my bank details , its around 20 days time and they didn’t collect faulty power bank also didnt give refund yet. I called up so many times to them but they keep on telling it will be get collected soon. My complain id in askmebazaar is QRC497030