Prebuilt warranty question

[TheGentry]

I bought a custom PC from a competitor it came with a 3 year warranty. It also came with a Gigabyte 4070 which has a 4 year warranty. They never provided me with the box for the GPU but also did not give me the check number to register the warranty after back and forth. They said the box has been recycled they can't get it, then they said they would check camera in build room to see if they could get it. After that failed aswell there last response has been

"As for your requested check number I regret to inform you that this cannot be provided. This is in part due to the PC being built by us, as once a member of our engineering team opens your chosen components, they no longer qualify as "brand new" with their respective manufacturers"

Is this correct I'm so confused by this anyone got experience or advise

 

[Tetras]

Is this correct I'm so confused by this anyone got experience or advise

I don't know about correct, but it is normal. If you buy a prebuilt computer you usually just get their warranty, even if e.g. you have a PSU with a 10 year warranty. They often fit oem rather than retail parts too, so there's no way of knowing if the warranty would be user redeemable anyway, or what the original purchase was.