I redeemed a Tesco gift card, but the value is £0, why?

That's weird. How did that happen. I have never redeemed a Tesco card, I always do Amazon but still, it should never be empty. Contact customer service and lay yje complain to them. 

Esy kese hooo skta hai

This is the first time this has happened to me. I sent an email to Support, and I hope to receive a response soon. Thank you.