Issue with update 'End Contract Date' of Contingent Worker 'Edit_Service_Dates_Request'

I'm trying to update the Contract End Date of a contingent worker through the SOAP api endpoint 

'Edit_Service_Dates_Request'
I'm having trouble to get the correct request body and always get a error back that complaints about validation errors for Seniority_Date, Original_Hire_Date and Time_Off_Service_Date

I tried with only Contract_End_Date, included empty values for the fields with validation errors and even added dates for them, but that throughs other errors. 
What I'm I missing here?

https://preview.redd.it/jndpiu7jljhe1.png?width=1332&format=png&auto=webp&s=97201b86eb83498db98135584d390bb57d4ee15b

https://preview.redd.it/bt1tiu7jljhe1.png?width=1360&format=png&auto=webp&s=02f8e923be7312d61c2445cb327d86cfa655677f

https://preview.redd.it/xkbo2w7jljhe1.png?width=1364&format=png&auto=webp&s=0ed68c87d431f2a54e506df98002a7f6e4b4c343