Change the name of your app to "Send Receipts Via Email" or some variant. Also, the "1000 receipt" credit for $0.99 makes no sense..either make it a paid app or sell something like 20 receipts for $1.99 via IAP.
Does your free version have any ads? Anyway, if you want to give up on the app, I'll happily buy the source code from you for $100