I know a speech pathologist (think speech therapy for kids) who also does accent reduction for adults. It's a lot of the same type of thing: learn to make this sound with a different part of your mouth, then practice until you can do it without thinking, and since adults tend to be less cooerced and more engaged, it can go quite quickly.

Without trying to be mean, your writing could use work too. Practice writing more formally: have instead of got (mostly); capitalize things that need capitals, like English and I; spell check; full sentances with subjects and verbs; a space after sentances.