While fixing new listing account by mistake I have confirmed that I am using a channel manager (I don't have one and I'm not plannig to get it)

Hi 

Yes you can disconnect it , If I remeber right its under one of the pages in the Account menu top right.

else call partner support

If needed, Simply report to BdC Partner Support , see below 3 methods.

Message or Call BdC PartnerSupport ***

1. In the extranet, go to the ‘Inbox’ tab.
2. Select ‘Booking.com messages’.
3. Right Pane - Click on ‘See Contact Options’. 
4. Choose Account
5. Now choose Other
6. Then at bottom , See all contact options, and click Message or Call
7. As there is no one number for all partners, the number for your nearest BdC Partner Support is then revealed.

8.  

   *** public main lines via Where you can reach us

    

    

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