How to Register my ASUS 18W USB-C Adaptor

[SallyC]

System: N/A
Battery or AC: Battery
Model: ASUS 18W USB-C Adaptor
Frequency of occurrence: continuous
Reset OS: N/A
Screenshot or video: N/A
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BEFORE you send me all the links to "how to find serial number" or "how to register", I can confirm that i have tried all that, and get "Incorrect serial number" when I submit the form. The serial number for the item i wish to register, so as to get warranty, is L3NYCV000339116. Purchased bia Amazon UK from Techlovers Ltd based in UK (at 20-22 Wenlock Road, London, London, N1 7GU). So please advise how i should register this item, which at a cost of £76 is not a throw-away if it stops working. Thank you.

[Blake_ASUS]

Hello Sally,
May you help to clean the cookies of the website and try again?
I am able to key in the SN for register and the product type shown itself.

Thank you.