Could you please explain why the excellent collaboration is the cause of the approval? I'm not sure if I understand the intended meaning of the sentence, and it would help to choose between 'approval' and 'confirmation' (or write in French, I speak French).

penguin, thank you very much for your swift response.

This person is the director of a travel agency.

She has booked a stay in one of our holiday residences and is asking to pay her bill when she arrives instead now by bank transfer.

She knows me but for the payments only the manager of the residence is responsible.

As I am OK to accept it, the manager will also confirm her approval.

I hope it helps you to better understand.

OK. In which case I would say:

In view of our excellent business relationship either our Director or the booking department will approve your payment request shortly.

Thank you very much indeed for your help.

Have a great day!