Sangeetha Mobiles — Why people dont buy from stores especially Sangeetha Mobiles

I by mistake dropped into a Sangeetha store to purchase a mobile (Samsung M02) yesterday i.e. 27th Aug 2021. I told them it is a gift and need not open it trusting there would not be any issues with the piece. I gifted it and within 2 hours the person says the phone gets heated up like an oven, I immediately called the store and informed them about this and they mentioned I need to get the phone back.
I was so embarrassed and had to apply for permission at the office went all the way to his house and got the phone back just to hear that I need to use the phone for 24 hours and then check if there is still an issue. The executive reset the settings and gave the phone back to me. I kept the phone for charge and within 2 hours I called them back saying the phone is still having issues. The executive asked me to get the phone back at 9:45 am today i.e. 28th Aug 2021, and promised would return a new phone by afternoon, but while I checked with the store the executive says he would get this phone serviced and would get back this phone by afternoon.
I told them I need to speak to the Store Manager who happily receives the store executive's phone but while I called says he is in a meeting would call in the afternoon. I called customer care to explain this issue and their seniors also are busy and asked me to drop an email.
If everyone in Sangeetha mobiles is busy why have customer Support?
My issues:
1. I purchased the phone at 10 am, got the billing done at 3 pm for 8000/- whereas i paid 8500/-, the balance 500/- they said they would give me headphones and no bills for that. 2. I have raised the alarm before my billing is done, why have i not been replaced with a new mobile?3. Do I need to visit a hundred times to just buy one phone?4. I even asked if I can upgrade and buy a better phone but they strictly said we will rectify this phone and give no replacement.
Can someone senior please get in touch with me in case you did not understand this issue.
Invoice # DI/KTR/170