IDK Kuwait. I'd say take them to the store first and than call sapphire.
As long as Sapphire has a official retailer in your country you should get new ones.
Going to the store at 8 A.M tomorrow..
Will demand a replacement GPU and riser.. I'll play dumb and say I don't know about sapphire, etc..
"I bought these from you and now they're not working, you said 3 year warranty"
good luck trying to play dumb its a bad idea since you already know. taking it back to the retail place will be useless, gpus have to be sent back to the manufacturer not the place of which you bought it from, btw most warranties come from the manufacturer. I'm currently RMAing a sapphire tech gpu, more specifically an rx 480 8gb OC, don't send out that gpu out before restoring the original bios, btw when doing RMA you have to pay for the shipping to ship the gpu to there facility and on a side note they do bench them and check bios's