credit balance website

I need a website that keeps a credit balance for my visitors. My visitors will NEVER need to sign up on my site. All they will can do is view their credit balance, view past transactions,? and browse the website information. How the system will work is in the admin, i will need to be able to credit/deduct credit from their balace and also leave a description. All transactions will need to be stored so my visitors can view them and as well, I need to be able to view em in the admin section. How the site works is I receive payments from my visitors via another website.? I then manually add the credits to their balance on my site. The information that I will be entering are as follows... **Nick Name**(Must recognize if this Name already has a credit balace) - if not in the system yet, it needs to create one **Amount** - There must be two buttons for this option(Credit)(Deduct) **Description** - Small text area for reason for the credit/debit Please note i may want to automate the crediting of accounts with an email parser Members will be able to search their credit balance by entering their Nick Name from the other website I am receive funds from them.? THe charactor sets for that site are not just the standard, they have some wierd letter charactors they allow so the Nick Name field will need to support that.