Manually updating donor credit cards and other info creates significant problems:
1. Creates opportunity for error
2. Inconsistent with norms and therefore creates discomfort on donor's part (they don't want to call/email, provide personal details to someone they don't know, etc)
3. Huge amount of time

Perhaps most importantly, what if a donor wants to stop donating? They should be able to manage that themselves.

Thank you for considering.