plain and simple - a coil is gone. Coil will cost 70e and take 10/20min to replace by a mechanic.
Some garages reckon that all 4 should be replaced when one goes, I don't go with that... Your garage man probably wasn't able to figure out which coil was gone so just replaced all 4.
Also don't let this go on for long, you are effectivly running on 4 cylindars, you have fuel that is not being ignited properly which will destroy the cat converter. Also the rocking back and forth of the engine, can do damage to engine mounts, loosen up components etc.
It is concievable that 2 coils went in such a short period of time, just unlucky, but 3 I kinda doubt that, I reckon he just wasn't able to figure out which coils were gone the first time. Was a bit easier when they went a 2nd time..