Income tax notice reply

I am a distributor of Paytm payments bank which deals with money trasfer business. Now we have many retailers under us which deals with us. We provide retailers with money (digital form) to perform money transfer from their shops and the retails collect cash from the person who came to do money transfer. Now we collect this cash from retailer and deposit in our current account and then send it to our paytm distributor portal and the process moves as explained above. Basically for example we have invested 10 lakhs and the same money is rotated every day. Due to deposit of huge amount at our current accout, income tax department has sent 131(1) notice. Now how to answer that this is not by income but the commission that we receive by doing money transfer is our income? I file gst returns for the commission I receive.