posted by Writeacher on .
The preposition after "inquiry" should be "about," not "on."
Also, "the above mentioned" what? It's not clear what "the above mentioned" is (needs a noun after this phrase), so it would be better to write exactly what is being asked about -- example: Thank you for your inquiry about your washing machine.
If you're asking about punctuation, there are no errors. It's just a bad sentence!
Thank you for your inquiry on the above mentioned.
Is the above sentence correct?
Thank you for your advice.