SEO Business Invoicing Software

I need a software that automatically creates and emails invoices for Search Engine Optimization clients. In addition, The software must have the ability to check Keyword(s) rankings for each particular client, and then include those keyword rankings along with the +/- changes from the previous month. I'm not a programmer, but I had imagined... 1. Input client information (business details, Domain, Keywords) 2. Input schedule for monthly billing date. 3. When the date arrives, the software automatically generates an invoice, pulls & records KW ranking data, and then emails the client the invoice along with ranking data. The software should have the ability to work both with manual input, along with automatically on a pre-set scheduled basis. Also, if there are multiple invoices for one day, the software can randomize the generation & email time to avoid any complications/crashes (as long as it's before 5pm, business closing time). I currently work with 12 SEO clients, but the software should be light weight and able to support hundreds of clients without any problems. Please ask me any questions... Thanks