Invens phones

i bought invens v12 plus smart phone last year, hardly two months already phone started over heating, freezes and won't start, took it back to the store, they reset it and last only two days and still experience the same things over and over again, and then all of a sudden it automatically switches off... have to take out a battery to restart. worse now can't operate whatsapp on this phone cos it keeps log me out and says number not registered on the phone.... this is the worse worse worse.....terrible terrible terrible phone even. its beautiful for nothing. wrote emails to the company but no respond even today.