Vim Remove/Insert using Visual block select after a colon

Vim Remove/Insert using Visual block select after a colon

I've got this piece of code:
fill_in "Name",with: "John"
fill_in "Email",with: "user@example.com"
fill_in "Password",with: "supersafe"
I would like to replace everything that is written after : with user., so
I can complete the code by just adding name, email and password,
accordingly after the user..
fill_in "Name",with: user.name
fill_in "Email",with: user.email
fill_in "Password",with: user.password
Moreover, a way (maybe a vim plugin?) to navigate from one line of the
visual block selected to the other would be just optimal of course, though
not the main point here.
A simpler option would be to instead of replacing it with user., just
delete it with d$; however the selection issue still stands.
I tried it with normal Ctrl-V selection but since the : characters are
placed in different columns of each line, I don't have the desired
behaviour.
thanks