Zen Cart Upgrade

I am wanting to upgrade a zen cart website from version 1.3.7 to 1.3.8 there are several add ons installed which will need to be integrated. There are a few orders a day that come through the site and a thousand or so customers. ## Deliverables The website in question is [login to view URL] It is running version 1.3.7 and I want to upgrade to the latest version 1.3.8 The reason for the upgrade is to keep the security up to date and there has been a but with orders, which some forum posts say an upgrade may fix the issue. The issue is that some orders places get the same order number which sends my client (owner of Kivalin) an email that an order has been placed but only inputs one in the zencart admin. I am guessing the orders happen in close succession and the second order overrides the first in the database. I think all the modules installed above are standard and not modified; except there is one other that I have hard coded in myself which is the campaign monitor intigration which I have edited about 3 files ( a search "campaign" finds all the files). It is utilising API keys to send new customers an subscribers to campaign monitor. I would prefer to send the database and all the files so I can see a live functioning version of the site, then do the change over once we are happy. I am new to ret a coder, if there is anything I have missed please drop me a message. Jake