Urgent request, please I want to correct this letter, and to add thankful at the bott

I am a student at the X University, and had applied to the University in April -2012 to get the CAS Letter from the International office of X University. At the international office’s desk, Through lack of knowledge of the employee met me in the estimation of position assured me that I have right to renew my visa from within UK and she gave me the CAS application form which I submitted next day. On Thursday, 24-5-2012 I was contacted by the international Office of X University, and told me that I should leave the United Kingdom prior to violate the day 31-5-2012 because we can’t offer the CAS letter for you . I attached all what happened at the international office, and explaining all the problems which I facing now. .....