PDF Invoice to XML conversion

Hi.

We are a manufacturing company and receive numerous Purchase Orders and Invoices via email as a PDF.

We spend a lot of time typing this information in, is there a software/service out there that will allow me to convert these PDFs into useable XML so I can import it? I've tried a bunch of "PDF to XML" converters but they don't do anything other than export the internal tags which does nothing. I need a XML document that is clean and useable.

Many thanks for your help if I could solve this one.

Jason.