If they are calling you at work, you tell them that they may not call you at work and then they have to stop. You can also go to your account profile and delete or change your phone number there.

It is ridiculous that they can change a contract at any time, hiking fees to insane amounts. When I (if I ever!) get my modest credit balances paid off, I will never have a credit card again. I will be my own creditor by way of a savings account.