First of all, let me tell you that liana and swift have same engine & therefore have same coils.
The problem you are facing is probably because your mechnic had installed kabli coils instead of new ones OR had Nitto tapped the old ones OR has put new but chinese coils which rarely last more than 3-4 months. Moreover, probably you get the engine bay washed with water during car servicing.... DON'T do this.
1- Get orginal coils installed. Go to a known suzuki genuine parts dealer & purchase new ones yourself. Don't go for chinese or kabli ones.
2- Check spark plugs as well & change them too if required.
3- From now onwards, don't get engine bay washed during car servicing.