Spicejet - Flight cancelled Ticket money not refunded

I had a flight on *th September ****, from Guwahati to Bagdogra, time: **:**, reached the airport ontime, collected the boarding pass, completed the security check and stayed at the boarding gate, however, a message came stating of delay for * hour and then another of * plus hour and then another, finally the announcement was made that the flight will be on **:**, After the time arrived, no announcement was made not boarding started until **:**, then suddenly the ground staff said flight is cancelled until further notice and cancellation can be initiated, which will be refunded by * working days, which I did and they provided me with a slip with stamp and wrote full refund with signature on it.
But till date nothing has come up. I tried sending whatsapp message, no response. Is this some kind of fraud or a carelessness towards customer.