Graduate / Proof of English proficiency I really need your advice and corrections [5]

Proof of English proficiency. I really need your advice, suggestions, and corrections for my letter.
Appreciate all your help. Thanks in advance.

I'm asked to attach a declaration or certificate of English proficiency for phd application
As I have no certificates proving my linguistic skills

I respectfully present the following justification of my English proficiency.

From intermediate education on wards, English was the medium of instruction in our core subjects, namely reading, writing, mathematics and statistics.

I studied at JBR, Delhi. I graduated with a Bachelor of Science degree and post graduated with a Master of Business Administration degree. The official medium of communication was English. All projects, assignments, seminars and group discussion were always conducted in English.

I can humbly say that I passed all English subjects with above-average grades.

After I finished my Master of Business Administration degree, I was employed with one of the top University College. As a Lecture, I was responsible for to teach a guide a class for 96 post graduate students at XYZ Group of Institutions. I was required to communicate in English with students as well as employees. To get more exposure I have also attended some software training. In all of these instances, English was the medium of communication.

After working in India for couple of years, I was gone to South Africa. I worked in South Africa for almost 2 years as software professional. Of course, English was the only medium of communication used during my employment period in South Arica.

Presently, I'm a Lead Database Administrator with one of National's largest consulting Company. I have been employed with KCG from last 1 years and 8 months. In KCG, the medium of communication is exclusively English. Our clients are located only in South Africa. English, both written and oral, is the only medium of communication during interactions with clients English is the only medium of communication with clients during meetings and discussion.

As a professional interacting with a range of clients located in South Africa, I consider myself to have a high level of proficiency in both spoken and written English.

Regards,