I haven't received a payment since September

Please, help.

I am renting an apartment through booking.com and have not received payment for September and October.

I have been trying to get in touch with someone ever since but to no avail.  I wrote them messages, but I did not receive a concrete answer, only that they received a message and that they would respond, but none of that.

I don't know what else to do. It is not clear to me how this can happen. I duly received guests in the apartment who booked me through booking and for that I did not receive the money I earned. 

On top of all that, booking charges me with not paying them a commission, even though I didn't get the money they were supposed to pay me less the commission.

Please help !!!

Katarina