Please take note on any GIRO form you sign, say you owe them $10 & say for 6 mths they "forgot" to deduct, on the 7th month they remember, they will deduct what you owe them, that is $600 + $10 for current month....you have $610 in your account, it will be emptied zero & you do not monitor the account. Soon, you receive notice that your account is below the MINIMUM SUM & fees of $2 or?? will be levied.
As for your case, you cancel the GIRO...you clear your account of any money, except for the least amount in the account $10....do not trust them or any bank to carry out this cancellation on time, they are very sneaky, they want that money, so do not encourage them. If you a re using credit card, with all the evidence, claim that amount back & any interest accrued too.
Use one account for GIRO payments ( if you are forced to), never credit your salary into that account ( NEVER), credit your salary & whatever extra money in another bank's account, one, you never take loan from, have credit cards or anything you have to pay.
Doing banking these days...it is like running a 'guerrilla war'...... if you have more than $25,000...consider keeping the extra in cookie jars at home....especially after the world cup, for all the winning you make from Mr. "X".... ha ha ha & you have time, bank in, in multiples of below $20,000.... banking these is also like running a 'covet' operation....IRAS is watching you.