Machan I know the best place. Go to London Business school situated in front of Bambalapitiya flats .They are conduting classes and diploma programs for English. There is a madam called Nirosha. Just have a chat with her and see the vast knowledge and accent she posses.Can't think she is sri lankan.Tremendous vocabulary and specking no one can beat her in English. She is so friendly. Hurryyy..She is conducting IELTS classes and perfect..