Arabic-english accent

Dear forum-ers,

I was born in the UK and acquired the english language as a joint first language with arabic. My family moved back to our country when I was still a child, and although I always maintained a very high standard of spoken, and written english I unfortunately lost my accent.

I moved back to the UK 2 years ago, and am working in a job that requires interaction with lots of people from different educational backgrounds. Everybody commends me on my excellent grasp of the english language, but they can easily tell that I am a foreigner. I don't want to be a sell-out, but I believe that, especially recently, an arabic accent is associated with a negative racial stereotype.

The problem is I am getting very stressed, and insecure about my accent. Some people say that it is very subtle, and kind of intellectual sounding. Other people (my friends) can sometimes make fun of it, and although they mean no harm I am deeply shaken by this. I am sure lots of you know that the pronunciation of certain consonants and vowels is very heavy in arabic and I have been trying to consciously alter this, but I fear sounding fake. The letters I have special problems with are the Rs and Ls. Any way to change this?

PS. I need this for professional advancement, as people in my position get more recognition when they sound more 'local'.

Thanks