Welcome to our Community and thanks so much for your first post - I was sorry to understand that you have noticed a fault with the free TV that you have been sent.
You advise you've had it between 3-4 weeks. If you have had it less than 28 days, you can contact Extertis directly on 01282 858 484. They supply the hardware gifts on our behalf and will be able to assist you with a replacement.
If you have gone over the 28 days, you will need to contact the manufacturer directly as they would supply you with a 1 year Warranty with the equipment.