PayTM - Voucher had expired before the date

I have purchased a central voucher on ** Feb **** on paytm which has validation for ** months that is till ** Feb ****. But when I tried to access the coupon on ** Feb **** it shows nothing but the order is being processed. I got a doubt and went to central mall punjaguuta Hyderabad on ** Feb ****. They said that the coupon was already expired. I soon tried to contact customer care they said it was not in there domain. They asked to raise a query regarding the issue which I did and after that, they sent a message like they are looking into it and will reply in ** hrs. I said to resolve it soon so I can use it in time but after * days they are saying now the voucher is expired. So the issue is closed then I tried to explain that query was raised before the expire date itself so it's not my mistake you didn't solve in time. They took two days to repeat the same automated message without even looking above details given by me and I demanded for call to explain my concern to them clearly to which they called and agreed they understood wrongly and promised me to get back with solution by call in two days but after * days they just simply repeated the message and closed my query as resolved and blocked all my calling options to them this made me sick and mentally torched. I want my right as a consumer and want my money back.