Welsh ISC does not have a remit to deal with school complaints or offer advice regarding complaints.

Contact the school directly
Depending on your concern, the usual route for a complaint would be:
1. The Head Teacher: any issues concerning the general running of the school would need to be addressed to the Head in the first instance.
2. The School Complaints Policy: all schools will have a policy governing their handling of parental complaints. This will be available on request from the school, if it has not already been given to you.
3. The Governing Body: if you feel a complaint to a Head has not been answered satisfactorily, you could consider an appeal to the board of governors/proprietor/owners in writing.

You may also wish to consult the Welsh Government or Estyn on what to do if you have concerns about an independent school.