We have a Mazda 3, 2006 and I can move the gear stick to 'park'. It's an automatic.

Is this easily fixed? Can anyone suggest if I could fix it myself or take it to the local mechanic or if it's complicated, take it to the mazda centre?

I would not take to local mechanic. Take it to Mazda service there charges are same and they might say we know what it is as have same problems before.

Sounds like something is blocking the linkage or needs a slight adjustment.

Usually it is easy and not expensive

Are these M3's any good?? Been wondering why so few posts about 'em.

If you can not get it out of Park, its usually due to default brakelights. Brakelightsignal needed to release, or push a button next to stick. Some cars need brakelight to get into Park too.