Hathway — Refund for modem

Having experienced once on being deceived of not refunding the amount on return of modem, I have retained the modem.
I am getting calls for the same.

I wish to know why Hathway has been doing this. What is the actual idea behind promising the customer that you will pay for the modem later but return it now... When I have been a victim of the similar kind.

So please stop calling me in this regard or make the payment and take back the modem.

My number may be put under DND. Complaint will be made if any further calls are received in this regard.