Review on Portable battery Samsung EB-PЗ300, dark gray by Celina Kretkowska ᠌

Bought a month ago. Got a chance to try it! Went on a trip, charged. We drove 8 hours. On the way, I connected the phone sam 22ultra, listened to music. Died 4 hours later. Arrived, charged again. On the bodies it was 25% set for the night to be charged from the drive (charged by 100%) in the morning I saw a dead drive, and on the bodies 85% ! Is this a marriage? Or maybe I'm doing something wrong? In general, for me, it turned out to be completely useless! I'll have to buy another, more powerful one! Can you please tell me if this can be returned?