not showing bank detail tab in finance tab on my booking.com account

Hi

That will be because there aren't any Tabbed views in the Extranet.

Look for Finance > Finance Overview,  that has the bank information for adding BdC as a Payee to your bank account

Message Finance Topic

1. In the extranet, go to the ‘Inbox’ tab.
2. Select ‘Booking.com messages’.
3. Right Pane - Click on ‘See Contact Options’. 
4. Choose Finance
5. Now choose Subtopic
6. Follow prompts.

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.

Kind regards