Booking.com complaint: Flight cancelation and rebooking procedure

GoToGate.com partner with booking.com
almost wasted 2 days to reaching them,
I requested a call back from supervisor yesterday, and call service agent told me someone will be back within 24hours. No one contacted back, It’s really frustrating now, very poor customer service.
after staying on hold for more than 2 hour twice, as call disconnected it self first time. speak with another agent, who seems to insisting for refund and not providing proper alternative way. we booked flight on 12 Dec,2021. and when time for travelling comes close they are only providing solution with refunding money after deducting administrative charges.
As this ticket belongs to my mother who has difficulty in walking and also language barrier, so we book this flight as our relative travelling on same flight. But all sudden Airline make changes and put them on different flights, earlier they put both on 23rd March later they make changes in my Mother flight and reschedule for 21st March from Delhi to Montreal and 24th March from Montreal to Edmonton, more than 48hour delay between connecting flights, how you treat customers who need special assistance.
We need to sort this out as soon as possible.
Thanks