Gmail customer care can't help you retrieve your account

This email account is great, but when you lose your cell number for access to your account via your phone it's a problem and if you decide to use a new number Gmail doesn't make it easy for you to retrieve your your account. They say they'll send you a password change in 24 hour which never happens. I don't understand why all the other account verification becomes worthless or why they can't say go to your computer's email login and go to settings to change your cell number there. Why not?