Vistara — Boarding denial - staff said not LEGIT rtpcr

Flight 18th feb 2022
Reached airport at check in counter and showed children rt pcr report under 12 unvaccinated (as no vaccination for under 12 at the moment ).
Supervisor called dev questioned the report saying NOT legit . I’ve signed self declaration form so why would he question it. Was he checking everyone forms to see if legit . He scanned the qr code which is breach of my children data and still questioned the authenticity of the report and did not let us board . If he had doubts of the report he should inform Indian authorities and he can’t question the authenticity. I’ve been emailing vistara and asking for full refund of tickets and if not received will take the matter to uk court