Private English lessons to kids

We are looking for a private English teacher to our 2 sons (13 and 10 years), once a week 1 hour per each son. Tuesdays or Thursdays from 16:00 to 18:00. English should be on a level of a native speaker, preferably also being able to explain in Czech. We are Czech family, living in Prague 5. Boys are used to such private lessons on regular basis, also studying English at school.