API Interface for A2Billing

I am always being asked to custom the a2billing customer UI and also I need integrate a2billing functions into websites .now I build one in wordpress,u can see demo here(see private message) I hope this is what u need ,basically you have one website ,and u also want customer register,and login to check his balance,account information ,etc I think my current work is good start for you,I can do more for you according to your requirements