Faulty Cat Phone needed to be raplaced or repaired

I upgraded my phone in December last year only to find that it was a faulty phone and it could not be repaired after a month I have heard nothing from the store and a am without a phone. I have sent a number of mails with no reply. This is the worst service I have ever encountered. I have gone so far as to ask Caterpillar the maker of the phone for assistance without any success. They also have the worst service for the small consumer ever. And would like to no what they are willing to do in this regard. Please some one help me to make these big companies aware of the small guys.