First, what's your aim? To improve your English or to study abroad? TOEFL or IELTS?
+ Simply, if you wanna improve your English, I think you can buy some books and learn them whenever you like (or in spare time). I just know 2 of them which seem to be interesting:
- Insight into IELTS (Cambridge University Press, with cassette).
- IELTS to success (Hawthorn institute of education, with two audio cassettes)
+ If you have the target to study abroad and want to take IELTS, maybe: Cat Linh Language, Apollo, Ausil..etc but I highly recommend this address:
The Education Company
21 Vạn Bảo, Ba Đình, Hà Nội.
( Ask Ms. Nguyệt or Mrs. Jacky Dyer (she has been an IELTS Examiner for a long time, working in Hanoi)).
This address I have heard several times and some ppl from here were really successful in talking scholarships, e.g, one won a FULL-scholarship of Australia ( AusAid) with IELTS band 7.5. Besides, the cost of an IELTS course is acceptable.
Further info, you should contact them directly.
Cheers. See ya...next year.