Currently using v1.3.8a of Zen Cart with PayPal IPN - Website Payments Standard

Have Zen Cart setup and running using a Paypal account however we need to change it. For example, payments are currently made through [email protected] but they now need to be made through [email protected]

The problem is that on switching the account over to using payments@ any orders placed do not show, although the customer and the shop get a receipt email from Paypal.

Once we switch back to using customerservice@ they go through okay. Also, the order number sequence doesn't show the missing 2 orders.

I need to get the 2 missing orders out of the system and find a way of switching over the Paypal account used.

Any suggestions?

Thanks