If you are willing to invest I can provide a better solution. I can make a software to intgrate with DHL API.
You have a list of clients that payed and you click and send the data tou DHL.
Relevant Skills and Experience
C#, API, Paypal, DHL API.
Proposed Milestones
$700 USD - First Version of the program.
$200 USD - Pass DHL Certification.
$100 USD - Debugging. Project Completion.