Symphony Limited — Touch 55 air cooler not cooling

Hi,
My brother bought symphony touch 55 air cooler on 14 th june 2020. From that day only, the cooler was not cooling the room at all. As per given information on there site,
It is suppose to give cool air for room of size 71 cubic metre. This cooler was not cooling at all and felt like a normal fan is running. We complained on symphony site also. They sent their service engineer, he said every part is fine and cooler will work like this only (Work like normal fan and will not give cool air).
But it is true touch 55 is not worth buying at all. I don't understand where else to complain. Kindly help with our issue, what could be done in this case.