Nucharge locking accounts for multiple users

[mo42nyy]

My brother just created a nucharge account on my computer so they locked both accounts
I called up and told them that we use the same computer and they unlocked them
However the woman i spoke to informed me that our accounts will be locked any time this happens (ie he logs in the i log in on the same computer)
How the hell do they know its the same computer and what i can do so they cant tell (aside from using different computers- due to their low loading limits onto the atm card i will max it out then call him and have him trasnfer money for me)