STC — stb stops working

I have bought stb from stc company on 01/05/2019 through amazon under a warranty of 6 months.
But the stb is stopped working after two month. I have tried to call their customer care but they are not attending our call. I request you to please work on this matter.
The setopbox has following details
Model no.-s600
Sr. No-151067
Please resolve the matter as soon as possible.


Attachment-bill


Thankyou