There's no limit to the number of balance transfers you can do but you can only transfer up to 95% of your available credit card limit.

Things you should know. 

Rate will apply to balance(s) transferred until that balance(s) is paid off.  All applications are subject to Westpac approval. You cannot transfer a balance from a Westpac card or loan. Balance Transfer Terms and Conditions  and lending criteria apply.  Payments made to your Westpac credit card will be applied to charges and interest accrued first, then to cash advances and purchases followed by the balance transferred. All purchases, cash advances and any unpaid interest or fees will incur interest at the standard purchase interest rate in accordance with the card's Conditions of Use. You can transfer up to 95% of your available credit card limit. Your card must remain within its credit limit after the balance has been transferred. Balances cannot be transferred to a Mastercard® BusinessCard/Purchasing Card. Balance transfers do not earn Airpoints Dollars™ or hotpoints®.