TPG is investigating an apparent system glitch that is skewing mobile account balances and initiating automated top-ups of a deposit set aside to pay excess usage charges.

A representative from the ISP confirmed the issue on the Whirlpool forums this morning. iTnews is seeking formal comment from a TPG spokesperson.
The first report of trouble appeared on Friday last week when users found they had 4.9 GB of remaining mobile data quota, exceeding the actual quota limit of their plans.
By Saturday morning, some users began noting the amount of call credits on their accounts had spiralled above half a million dollars. Other users reported even higher credit amounts being applied to their accounts.
A number of users also reported receiving emails advising that a mobile phone prepayment deposit — held by TPG to cover things like excess charges — had fallen below minimum levels, initiating credit card charges to restore the balance.
Some users reported top-ups that ran into the hundreds of dollars, though they were being refunded.
It was unclear how many customers had been affected by the issues. Customers were being advised to contact TPG to seek resolution.
iTnews will update this story once comment is received from the carrier.