You will need your AquaGib statements for the past 12 months to hand. If these are not handy, AquaGib can provide you with a copy of your 12 month history free of charge.
Arm yourself with a statement that has your account number on it (top right) and call 41288, press 1 and ask the customer service representative for a 12 month history to be prepared for you. You will then have to pick it up from their offices - the 6th floor in Leanse Place, 50 Town Range.