We have a house in Samutprakarn and the mains water supply pipes that are on our property as well as the drainage pipes need replacing.

Over the years the soil level has sunk considerably and nowthe kitchen has no water supply or drzinage and the toilets block frequently.

Any recomendations on plumbers as this is too big of a job for me to do myself.

Before deciding on the solution, make sure you know the root issue.  IE: sunken pipes may not be the problem.  Finding someone competent to assess might be difficult, so good luck.