You become a financial institution and you can use the program on your website built with all kinds of user security features. If you lose their data to bad hands, you will get your ass sued..
May so be, however this is about paying your bill, why would a stranger pay my bill?
@Jolanta
A stranger would not pay your bill but they want to hack into your information by changing your password on the phone now and use the web later to hack the financial information. There may be myriad of ways they can do social engineering to use your bank or credit card information.
Two step security to do a transaction online or on the phone is considered a good security measure.