I feel helpless with booking.com, how to communicate directly with important questions? How to reach the financial department as I got an Invoice in March but no guest appeared? and so on I really need a personal support? It is extremely difficult and

I feel helpless with booking.com, how to communicate directly with important questions? How to reach the financial department as I got an Invoice in March but no guest appeared?  and so on I really need a personal support? It is extremely difficult and time consuming and not understandable to read 1000 pages and to recon all information's. what is missing at booking.com is a easy and fast communication like with Airbnb. please help