If you purchase an item and it doesnt work. The vendor replaces it with another non working item and it is past the 45 days. What can I do?

I purchased a cell phone from a vendor in Sep. Two weeks after I received it it stopped working. I contacted the vendor and they sent a replacement. The same day I received it the phone didnot work. I contacted the vendor and all they wanted to do was replace the battery. The vendor has not provided me a working  phone from day one of the purchase. What can I do since it is now 45 days past the purchase?