Binatone 3.5" gps
The keypad doesn't work and leads to wrong directions

I bought a navigator named binatone 3.5" GPS ($99) from coles in braybook, tottenham. the customer service in coles said it has 1 yr warrentybut they didn't give me any warrenty card . but after about 7 months it didn't work . if i try to type 'A' the letter next to it comes. so i went there to complain about it there, now they asked for a warrenty card which i don't have and they asked if i have the box .but who will keep the box of something for 7 months, they know i bought it from there but they refuse to exchange it or fix it.. my question is IS THAT WHAT YOU WRITE IN ALL YOUR PRODUCTS, IF YOU ARE NOT 100% SATISFIED, LET US KNOW AND WE WILL HAPPILY GIVE YOU A FULL REFUND OR REPLACEMENT
I have been customer of coles for so long but this time coles made me so disappointed...