I have just finished a listening and speaking and accent reduction course which was provided for free by my employer, Hero. It has helped my telephone communication skills enormously and your employer should provide this type of English training free of charge if they want to keep their business. The courses we used were Advanced Listening, Clear Speech Works and English by the Numbers. This week I am in Southall in England visiting my brother but it’s so cold! Good luck!
Giridharan (Mumbai)