Upon entering your DHL.de details, you may find that these details are unable to save and instead you receive the error:
"ERROR: Not all fields have been completed correctly. Check below and try again"
You may also notice that the billing numbers are removed from the edit page. A primary reason for this to happen is that the customer number (also known as the EKP) or the billing number(s) are not valid (at least in conjunction with eachother). A requirement of these two numbers are shown below:
The customer number needs to be a ten digit long number, such as 1234567890
The billing numbers need to be a 14 digit code, starting with the customer number's 10 digits. Such as 1234567890AB12
If the billing numbers you're submitting do not begin with the 10 digits of the customer number, these will be rejected as DHL.de require this to accept. If the customer number and the billing number(s) you have don't match this requirement, it's recommended that you reach out to DHL.de to clarify this.
If you have any questions from there, please feel free to Contact Support.