Trip.com complaint: My flight change requests keep getting canceled

I had my flights booked via Trip.com Sydney to Tallinn. Not once I was asked weather I was vaccinated or not, also never got sent relevant information about restrictions. On my ticket it says that flight is operated by Finnair. I have checked all destination requirements, checked Finnair requirements. There were no problem for me to travel.
When I was at the airport, our first flight was with Wantas to Bangkok and I was told I had to have exemption to get on the plain. Staff of qantas was not helpful and wasted a lot of my time . I couldn’t get through the trip.com to deal with the situation.
Qantas staff then gave us exemption forms to fill out and send us to the Gp at the airport. It was 50 min till the end off the boarding. I was able to get the exemption done but then they still kept us waiting and we were late on the plain.
We were offered one alternative only , but our exemption wouldn’t be accepted by Malaysian airlines . We were told.
Waited for another few hrs and then we were asked yo leave by police and told that qantas is not going yo serve us.
Ever since I have been trying to get help from trip.com Calling them everyday, getting the same response, have yo tell my story over and over.
Got authorisation by Finnair for trip.com to change my flight. Now every time I send the change request it gets canceled, even though I can see the flights are available on trip com , I still get refused.
Also been offered another flight by trip.com staff with British airways and Finnair. I told him that I was told that I have to use the same company as original booking. Qantas and Finnair
I was assured that it is still going to work as it is operated by Finnair
Guess what request was cancelled as that was a different airline
It’s been a week of constant phone calls, walking in circles, just can’t get to the end of it.
I haven’t seen my family for 3 years and they haven’t met my 2.5 yo daughter.
My daughter is suffering now because I can’t give her my all attention as I am constantly on the phone or on the chat with trip.com
I really need one person to look after me. I can’t talk to different person every day. It really is disheartening. I feel like I am emotionally not steady after all of this