You can just request the copy of your past invoice from your app.
It will automatically be sent instantly on your registered mobile address.
APP -> My Rides -> Past Trip -> Select Trip -> On top Right you will see an option to re-send invoice.
Alternatively, you can raise a support ticket here. It will take 1 working day to process it.
If you request via app, it will delivered instantly on your registered email
In case you would like to change / update your Email ID, you can update the same from My Profile Section. Then request invoice again. Invoice will be sent on new email address.