N73
Irrational behaviour (of mobile)

I purchased a Nokia 73 in Feb from a mobile store in Sarita Vihar New Delhi-110076. It has been giving me a special problem of suddenly getting switched off while in use. It used to recover after a while say 20 seconds and start-up. Today it got switched-off while in use but never recovered. It is still in OFF mode. Please let me know what I should do and why this problem.

My number is 9958705544. Please note: This phone is DEAD now!