Questions about example sentences with, and the definition and usage of "Wx"

A: Dear ------,
My name is ----- and I am a applicant for ------. I regret to inform you that due to the current state of my health I was left with no option but to miss the IELTS exam I originally expected to take on August 13th. As a consequence of this I am unable to submit a passing IELTS grade before the 31st of August as requested. I highly value this chance to move forward in my studies and I would like to do anything possible to avoid missing it. Therefore I would like to know whether or not the school can agree to accept my IELTS grade later than usual. Because seats for testing are in high demand, I can only apply for the exam on September 12th. The grades will not be sent out until September 25th. In order to ensure that I can receive my visa in time for reporting in at the beginning of the semester, can the school consider sending me a CAS? I sincerely hope that I will be able to find a resolution to this problem.