We haven't heard from you since we sent you the letter appealing your denial two mnths ago.

[tufguy]

John to insurance representative: We haven't heard from you since we sent you the letter appealing your denial two months ago.

Is my sentence correct?

 

[emsr2d2]

Fix the very obvious spelling error and we'll comment.

 

[tufguy]

Done

Fix the very obvious spelling error and we'll comment.

Done.

 

[emsr2d2]

John to insurance representative: We haven't heard from you since we sent you the letter appealing your denial two months ago.

Is my sentence correct?

Yes, it's grammatically correct. However, if I were to nitpick, I'd say it's not clear which happened two months ago - the letter of appeal or the original denial.