Srilankan Airlines — boarding pass denied

Boarding pass denied, even my family having a valid visa (2 months extended), tokyo immigration has provided the seal.
Due to lack of japanese visa awareness by airline counter staff simply they denied boarding pass in chennai airport without checking their counter part at tokyo/ proper immigration team. Staff told they need english supporting documents. Even after we provided they are not ready reschedule my family tickets.
My family suffered lot due to staff mistake, she has carried small kid and huge luggage to and fro from their home (~500km).
Airlines not taking any action on it.
So raising here the issue, i hope from here this could solved at least.