I have this charger, okay it might charge mobile phone devices fast but powerbank takes forever to charge, sometimes up to 40 hours. Also if you leave it unused the charge is not retained, within an hour it looses 30% of the power that it has, which eventually makes it pointless to have.
Basically, if you want to use this powerbank, you have to charge your mobile devices straight away after charging the powerbank for 40 hours.
Not a good purchase. don't waste your money.
I think your unit is faulty as mine keeps a charge and will charge an a couple of hrs