Sounds pretty ridiculous. The charger implements the typical CCCV cycle. When the charger stops blinking, it cuts off. So leaving the battery for another 10 hours in the charger will not make any difference.
The seller propably knows that he sells fake and just invents some strategies to give you the feeling that you make something wrong. I am pretty sure, that when you open the plastic case, you will find LiPo cells with about 1100 mAh.
Even when there would be cells in that format and weight, providing a higher capacity, they will most propably not be able to deliver the required current (C-rate) without overheating too fast.