Power companior failure

I have a power companion, which I bought from Amazon brand new in late August in US. Now it doesn't charge and when i press the button, blink amber 3 times.
I call to nearest dell office (in Thailand) and they tell me it's out of warranty, even it's about 3 month old, and i used it less than one month.
Serial number from back of the device KR-0R7CW8-71789-55D-A09Q-A01
How can I claim warranty case? I have invoice and purchase docs from Amazon, but it doesn't contain the serial number.