Lounge ceiling has a crack which seems to be following the joint between two pieces of plasterboard. It tends to wander from a straight line a little and its about 3 to 4 feet long. In certain light you can detect a slight around the crack. I repaired it with decorators caulk about 10 years ago but it has opened up again. A leak from the upstairs bathroom didn't help here. IMO the builders did not fasten the plasterboard properly in the first place. The ceiling has a light artex coating.
What's the best and least messy way to permanently repair this?