Rebate

When  I booked 3 tickets thru CheapOair .com. a message appears that there will be a $50 cash back rebate per each ticket. When I called the phone number provided to get more details of the procedure, I was made to understand that a cheque will be posted upon filling up a form and I am unable to see any form of this kind. Therefore, I need to know the correct way of claiming the rebte or obtaing the said form to fill up. My E-mail saad0505366733@gmail.com