"Thank you for writing me in regard to your concern," wrote a representative.

Is it acceptable to write "writing me" instead of "writing to me"?

Thank you,
John

Using write without the preposition 'to' is more common in the US than in the UK. Therefore, I that both are acceptable in American English, but I suspect the latter is preferable. In UK English, only the 'to me' version is correct.

hi! can you please help me to polish my grammar. I always confused using preposition. thanks! ^^

Here is a page about prepositions.

GM, what say you on this?