Booking.com complaint: Flight booking

i used this site(booking.com)to buy an air ticket to fly from Manila to new zealand my original flight was on 5 November 2022 but then suddenly there was an emergency at home that’s why i changed my flight into December 24,2022 and the date that i chose is all set up then i paid the difference.the time pass by until the date of 30 November came they emailed me saying that i need to contact them because there was a price hike on the date that i chose which is on 24 December and on that day we was soo stressed and depressed because my father in law was passed away that’s why I’ve been soo much stressed i thought my flight is already set but the truth is not i called them straight away to fix it but they all saying they can handle until my flight is almost near and there is no solution nor resolve the problem until now ive been stressed and don’t know what to do hope someone can help me regarding to this matter I’ve been wasting soo much time and money to call them especially they in other country also been soo disappointed to there customer service