Try by your own
によるポスト Victor Zamorano に スペイン フォーラム
No, I can't suggest you any special classes, I suppose any you can find wil be nice. What I suggest you instead is to talk with natives the most you can. Talk, talk, talk and listen, listen, listen. Don't be shy, Spaniards are very comprehensive with foreigners trying to speak Spanish, and even if we speak fast, it's quite easy to get the accent after a few time. And if you are in Madrid just walk around, read a lot (banners at first, then advertising, then news etc. you know, the usual staff).
If I can give you a hand with an especific question or term, I'll be glad to help!
Good luck!