Adidas — Not able use Voucher

Hi, I purchased a product in Jan and would like to exchange it but as there is no option of exchange and customer care executive asked me to return the product and suggested to place new order after getting refund. I followed same. I paid amount through credit card and voucher. I have received the amount paid through credit card and they haven't reactivated my voucher.
From Jan 27th I have been following up team but still they are keeping my request on hold and not getting proper updates or resolution.