Here are the steps -
1) Create a calculated field -
DATEDIFF('day',[Service Start Date],[Service End Date])
2) Put fields like below screenshot -
3) Change the axis format by going to the format of your day axis & put 'd' in custom date format.
FYI - This view is just for what data set you had provided. In your original scenario you have add some filters too because of month.
Time Difference_PS.twbx 9.6 KB