I had my guitar's neck straightened from a shop, the action now is very comfortable as compared to before but I'm still getting buzzing before the 12th frets on all strings but its too much in the G string. Should I take it back to the shop or can it be easily fixed at home? I have fender MZ5 Mexican strat. Also should my guitars neck be completely straight? The guy at the shop told me its fine but I read some articles that it should be a little concave forward.
Straightening a guitar's neck is easy to do at home - if you know what you're doing. You took it to a shop, because you felt they knew the job better. Take it back, explain the problem. It may be they've adjusted it too far, it may be the guitar won't take all the adjustment, it may be it just needs the action tweaking.Whichever, the job's been paid for and it's not a good 'un. If you can be there while it's being worked on, do that. At least you'll have some idea as to how the mechanics works for another time. Necks are rarely dead straight, there's usually a bit of relief - the strings need a bit of space in which to vibrate. Sounds like there's not quite enough on your guitar.