I made a mistake, applied for a wrong course of study during my oral interview. My originally selected course of study was economics.

Now, I am be needing to write a formal letter containing some big grammars to a university registrar. Here is my own format letter. And I will be needing an expert to making some suitable changes to it, big words and grammar should be included, please.

Dear Sir,
I sincerely wish to request for correction of a course. Somehow I accidentally applied for the wrong course (Actuarial Science) during the oral interview and it was an inadvertent mistake.
Therefore, I am writing to request that my course of study be effectively changed back to economics, because economics is only the incontrovertibly irresistible course I had ever wanted to study in this prestigious university.
I apologize for the mistake and any inconvenience it might have caused.
I have attached a copy of my credentials and other necessary documents for your consideration.
Hopping my request would be given a keen consideration and acceptance.