False Advertising

We app**** for an account on the 13th July and chose the item that we wanted. Went throughout the whole process and on the otem that we selected there was a big banner with a cash back promise. They then delivered our product on the next day not the same day the 14th July, Without thr cash back on delivery for two weeks I waited for the cash back I asked the salesman when will I be able to get the money and he came with long stories and yesterday the 29th July i went to the store to hear what's going on and they then all the sudden said there is no cash back on that item. But for 2 week the sales person couldn't tell me. This is false adverti*****t cause on the item there was a big banner instant cash back. Lewis has lost my respect.