Peachmode.com - Store Credit expired contrary to explicit claim that it has no expiry period

I had returned a product to Peachmode and at the time there was no option for refund to mode of payment so they mandatorily gave me store credit. Their email clearly stated, "The store credit does not have any validity period and can be used for multiple orders, as per credit availability.". After some time I tried to access my account but the site showed that my account did not exist. I contacted peachmode and they told me that the store credit had expired. I showed them their email which categorically said that the credit has no expiry period. To this they claimed to have sent me a system generated email informing me of change in store policy. I never received such a mail so I repeatedly requested them to share proof that they had sent me such an email. They simply then told me that they have no records. As a result I am being wrongfully deprived of Rs.****/- which Peachmode owes to me.