Not sure if this is a bug, a one off fluke or requires a change in zencart and how it captures / holds info to avoid the issue occuring

This has occured on 1.3.7 and I am wondering if the same process and therefore bug/possibility occurs/could occur with current version (which I am testing and yes am trying to get to a state where I can replace my live site and upgrade). Also uses sagepay form as the payment gateway.

Anyway, situation is that a product was sold and went through on sagepay at a particular price (email from sage pay confirms this) but the order confirmed at a higher price. The system price is currently at the higher price.

I think what has happened is a sale has been ended or turned off at the precise moment that the customer was confirming credit card details on sagepay so that the info with sagepay was at one price but the product price and the cart price changed and confirmed at the higher price.

How can a price be captured in the cart when confirm button is pressed and not change during this time whilst card is being processed. Has this happened to anyone else? What can be done to prevent it.?