Garena shells purchase through razer gold doesn't work

I bought some garena shells from razer gold and it all works until when i typed in the pin and serial code into garena razer gold pin payment thing , and it says the coupon is invalid or already consumed . I've send tickets to both garena and razer gold but I'm quite sure its razer gold issue since garena leads you to razer gold website to type in the pin and serial . I tried buying another garena shells just to see if its only a 1 time thing , but its just how I expected , its everytime . Razer gold's customer service is barely any help at all , its just an AI that keeps telling me to login to garena and type in the correct pin and serial , I haven't tried the service hotline but i would like to know about other experience first . Razer gold worked when I bought blizzard balance so I still have trust in this