Excellent product full setisfy but service is chargeable

I bought two 15 ltrs geysers at the same time. One is AO Smith and the other is Racold. I switch on both the geysers at 8 AM morning and both the equipment cut off after about 15 mins. But when I use AOSmith at 2PM, it's water is as hot as morning. But the Racold geyser water becomes cold. Kindly note, in the mean time, I haven't used hot water from any of the equipment.
Therefore DO NOT BUY RACOLD MAKE GEYSER.
I am now repenting for buying the Racold make geyser.