Upvote:1
The form asks for monthly income in the case of employment with another entity and annual income in the case of self-employment. You might have made a mistake by stating your annual income instead of your monthly income. You should check on your form. In this case, you should reapply, point out your error and your new application should be judged on its merits without prejudice. Just be more carefully filling the form.
If you did in fact state the correct income and the ECO had made an error on his/her refusal, you should email the UK's embassy in your country, the post that issued the refusal as well as UKVI's email service. They will sort it out.