I need someone to assist me as the avenues I tried isn't helping

I don't have a complaint yet, but I need assistance as I contacted the call center and also online chat and they can't assist me. I also emailed them with no response received. I booked a flight 8 months in advance and I had to be back at a certain time. The flight has now changed and I requested the same flight but they said no seats are available. I'm sure there are some seats available. Then I requested a complimentary hotel because now my transit is really long.. They can't give this also.. This is very inconvenient as I am traveling with 4 small kids and a baby. Please reach out