the worst counter service which I have ever experienced

I should check this site first before I screw my wife and my son's trip. the below is my case.

my wife and my son had booked flight from Osaka to Narita 11:55am-1:25pm on July 24th, in order to catch the Air Canada flight to Toronto at 5:00pm.
I Thought JetStar air was more convenience than Shingasen train, but I was wrong,
They arrived Kansai airport at 9:00 and after checked in luggage around 9:20am, they were waiting at the Gate,
about 10:20am they realized there was nobody else waiting for the gate,
then they figured out the flight has been canceled by checking departure information( there was no notification to them about cancelling from Jetstar, later I found a e-mail about cancellation in my email box, who are going to confirm the cancellation via e-mail after you have checked in?).
The worst part is that after then they had been held by Jetstar counter service over 2 hours when they tried to seek the solution to avoid missing Air Canada flight,
after long unprofessional service, finally Jetstar staff told them "Sorry, we are fully booked in the day, there are nothing we can help you, we are going to get your luggage back to you",
Jetstar should immediately help them to seek another solution after they found out their successor flight has been fully booked,
in those two hours they missed a few options which were still reasonable to catch air canada flight (included peach airline from Osaka to Narita).
"THANKS" JetStar counter service, now they stuck in Osaka airport, Air Canada tickets has to be cancelled, I am talking with travel agent and air canada right now, check if can rebook the tickets to toronto,
unknown how much it would be cost, Anyway I just want them to travel back home earlier after long stressful waiting/stuck in Osaka airport.

Domestic
Japan-Osaka (Kansai International)
Japan-Tokyo (Narita International)