Every plan has it's own bandwidth. You should not overuse your bandwidth. In some servers we might just allow some Gig of bandwidth to go beyond the specified one in the plan just in case a customer has accidentlaly over used the bandwidth. Depending on how much extra bandwidth you have used we might agree not to disconnect your server and help you pay for the extra bandwidth and go on only on condition that this over usage does not happen again.
With some of our servers you need to install your own bandwidth monitoring tools because we do not provide any sort of monitoring tools for the clients.
If we issue you an invoice you will agree to respect it and make the full payment.
If a customer has funds in his account and pays his invoices on time without any dispute we might agree to allow him overuse his bandwidth.