Performance is not at all go !!!

This bought a battery for Samsung SGH-U600 is poor.
Despite careful packaging, with instructions slipped inside, this battery is very inefficient or faulty.
Placed in my phone, it holds only two days charging in standby mode (that is to say without phone), and is out of service after 2:30 to 3:00 in conversation.
Minimalist and lamentable performance for this battery Cellonic, touted for its qualities of robustness and endurance !!! .
The old battery (no-name) I want to replace has more autonomy than new now, and has three years of intensive service !!! (And had a yield 4-6 times higher when new, at a lower cost.)
I will of course contact the seller for replacement or reimbursement, this article does not suit me at all.