unreliable company, insurance scam

Beware and stay away from this company - www.usps.com which located in Berkeley, California. I purchassed a new computer and I used their services for the delivery. I paid extra for the insurance and my package was lost but this company denied my insurance claim. It took more than three month and still I am unable to get my money back. This company doesn't seem reliable after such experience and is not recommended to anyone! Beware and better stay away!