Street Style Store — Refund not received and the refund voucher is invalid

I had ordered products from SSS before. As the quality of the products was very low I requested for return and refund. but the amount was not refunded to my account they provided a voucher where I could only spend that amount for their products and not only that they kept an expiry for this. how can they keep an expiry for the amount that should have been refunded? I kept looking for products but nothing was to my liking so I couldn't buy anything. I had the expiry till mid of August. bit when I tried to use that voucher it was not displayed. I tried contacting them through the customer care number but I couldn't reach them. i also contacted through their Instagram page but still no response. their service is very bad. I'm a student and I don't have any sources of income. so this amount is a huge amount for me.i hope a solution will be received.