Hi Hsueh,
I'm Sumit, here to answer your query at the Microsoft Community.
Apologies for any inconvenience you are experiencing. I am happy to help you today.
Surface is a premium brand - I don't think you can get spare parts for it except on eBay I am afraid.
Also, Via this thread:
https://answers.microsoft.com/en-us/windows/for...
Mine was doing the same. I just scratched the rest of the coating off and cleaned it with rubbing alcohol. (nice and shiny underneath) I will add a precut screen protector when I feel it is necessary. They sell them now in all colors. I like the way it looks now, better than before!
I hope you find this information useful. If you have any more questions, don't hesitate to reach out. Otherwise, please take a moment to rate the thread. Wishing you good luck!