Customer Payment Tracking Database Upgrade

I have a database program that holds customer details, tracks payments etc. The program is Access based and is fairly simple. The reports it produces is done in the datareport funciton of VB. I need some small changes made to it. For example, the customer payment report should track payments owing by having using the start date, payment amount field, and payment frequency field. However, the program does not calculate the running total of amount owing over a given period. Also a couple of other minor changes, such as date format etc. Working program must be tested before payment will be made. The program is available to be downloaded from [login to view URL] for any bidders to check out before bidding.