British Airways - Denied boarding by airline

Our family was unexpectedly denied boarding at the last minute by British Airways staff because our * year old child, who holds an Irish residence permit, was missing a visa not required for entry to Ireland. Both parents hold valid Irish residence permit. Ireland authorities do not require visa for a child under ** if accompanied by parents. Britisdh Airways staff's lack of knowledge about Ireland's visa requirements for children led to a wasted trip, significant stress, and financial loss to our family. "British Airways" error caused not only logistical and financial disruption but also significant emotional distress for our child, making a stressful situation even worse. On complaining the BA portal, they asked us to take our complaint to travel agent who would raise issue with the airline. This is completely weird. I went to the traval agent as well which is Makemytrip. They are not able to do anything and asking us to deal directly with the airline. I would request a refund fo the flight tickets as well as suitable compensation for the trouble caused to us.