Review Purchase of New Age brand power bank

I bought a new age brand of detachable power port and power bank on June 11, 2021. But alas barely three weeks after the power bank wasn't changing. It will change my fone but to recharge it's battery later wasnt working. I went back to complaint about the power bank but was told nothing can be done. This is at the Ire akari branch and despite I took everything to show proof andin fact the power bank was still looking very new.
I'm disappointed to say the least. Especially because I have bought oth charger and charging chords there. More so, there was no one to speak, to express my displeasure aside the sales guy at he front desk.
I do not think this is fair or how to treat a customer to say the least.