Tevo Magneto power station not delivering to its name.

I bought a Magneto 600w power station a month ago from OK Furniture in Fochville. On your packaging you claim this power station can fully charge within 5.5 hours. I rarely use it to below 90% and to charge it full again takes 3 or more hours. I am really disappointed with this purchase given the price tag attached to it. Today I used it to 97% I started charging it at 19:45 it showed on the display it was going to take 3 minutes to charge it full, it is now 20:20 and it is still at 99%. Can you maybe contact me because I am really disappointed with your product.