Defective unit sold and customer must bear the brunt!

I purchased a cell phone from Jet Store on 27/01/2018. The phone heats up when charging and using so much that you can barely hold it. I called to report this but was advised that I can only return the unit within 7 days as per the policy now since it is the ninth day, it will have to be taken in for repairs which takes up 2 three weeks. So now due to a defective phone that was sold to me, I need to wait 3 weeks for a phone that i have for less than 2 weeks!!! this is really unfair. Why must I be inconvenienced.

How does this works , I understand rule are meant for a reason and I am not disputing this but when a unit is defective within a month this calls for concern and exceptions should be made!