Virgin's BALANCE enquiry states CREDIT LIMIT!!!!!

I signed a new contract with Virgin for my 11 year old son. After receiving the phone I tried to set a limit on the account and was told I do not have a say in the limit as Virgin decides this limit. This is a poor practice.... Having a responsible child I told him how to do balance checks and to stay within his limits for data and calls. Then I received a statement more than double the monthly subscription. I went to the store and they told me the 'BALANCE ENQUIRY' feature actually states the amount available to the CREDIT LIMIT. How stupid is this. I have tried in vain to resolve this but the response is - 'Our customers prefer this and this is our way of doing it'. What nonsens. Then you must change this to CREDIT AVAILABLE and not call it a BALANCE ENQUIRY. And they refuse to set the account limit to what suits me. So be aware that although they might offer good value deals they lack in what industry standards are. All other networks you can decide your credit limit and you can check the AVAILABLE BALANCE. Poor from Virgin. And I also tried to get a detailed statement of the month in question and was sent a spreadsheet only programmers van read. No response since then.