I took the ISS classes. The teacher was good and the price was right (practically free since they are government sponsored; you just need to pay a registration fee).
For tones, I would recommend doing tone drills. This website is quite good. CSS
It may be boring, but just listen to it and try to repeat it every day several times a day. Have someone correct you sometimes and just keep at it. Do that for several months. If you don't improve, I'd be shocked.
And lots of listening practice also helps. Find some good Youtube channels or TVB shows (no news) and watch a bit every day.