Payment Card reauthorisation issue

HI

We have a problem where a sales order is created and paid for with a Payment Card.

The initial authorisation is made for the full order amount ok.

But where the order has more than one delivery, following the first delivery and Invoice the authorised amount is cleared of and when you come to create the second delivery there is not enough authorisation.

This is causing major headaches.

Does anyone have any advice to prevent this situation?

Many thanks