Powerbank from Dion Wired only lasts for a year

Purchased an expensive battery powerbank from Dion Wired Somerset Mall on 11 March 2018. Cost R449.00. It's not an item that I use very often. Purchased it for those emergency times when you don't want your cellphone to be without power. A few weeks ago I noticed that only one of the blue charge lights was going on during a charge. So I tested this for a week or so and then when I had some time on Sunday 24th March I took it into Dion Wired Somerset Mall. together with the original till slip. I was told categorically that they would not entertain replacing it because it was "out of the one-year warranty" period. Now I can't recall if there was any specific warranty stated on the units box and I have unfortunately either misplaced the box or it has been thrown away. The question arises: why doesn't Dion Wired warn customers that there is a chance that the products they are selling will not last more than a year. It was a MUVIT 12000mAh Power Bank. In case anyone is considering buying one. Be warned, it may only last 1 year and then you'll have to buy another one.