To check your balance on your Comdata Card you can go to cardholder.comdata.com or
https://cardholder.comdata.com and enter your login information or create an online account with comdata to check your card balance.
With the comdata card you can check your balance several different ways such as via either phone, the online portal or by free text.
I check my comdata balance through the online portal which is very easy at cardholder.comdata.com
The other ways are pretty easy too if you can't get access to the internet.