Actually, sorry to disagree with ya dude, but intonation is setting up the tuning on your guitar and string length compensation and doesn't have anything to do with buzzing frets.
Maybe you mean after you've raised the bridge first? Cause then you'd need to adjust the intonation to compensate for the change.

If raising the bridge doesn't help, and it's isolated to one or two specific frets, you might need anything from a refretting job to a simple filing down etc.. (time to call a pro if the guitar is worth fixing)
It might also be a slightly warped neck, so try adjusting the truss rod and waiting awhile for the neck to settle in.
If none of that works and it's not your playing style at fault, then it's probably time for a new guitar. Sometimes a guitar is a lost cause... sometimes you can work around it by using alternate chords or muting certain strings, buying lighter or heavier strings etc etc etc... but eventually it'll drive you nuts enough to move on to something new.