Sid Solutions - Refund not received

I purchased the security system from Sid solutions from their website- https://securitysystemstore.in. I also attached the purchase Invoice. I received all the products after * days except *tb hard disk. Then I contact the firm regarding the hard disk, then they told me to wait. After few days I requested them to cancel the shipment of hard disk as they told me that they are facing some problem in arrangement of hard disk and I also request them to process the refund of hard disk on ** Jan, then on ** Jan I received the confirmation regarding cancellation of hard disk and they told me that they will process the refund within *-*days. Till date, I did not receive my refund. They never pick the calls, they rarely reply on WhatsApp and emails. I have all the conversation on my email and WhatsApp.