Where did you get £3.6 billion from?
From the PDF:
"Continuing our efforts to protect the rights of workers who move from their
home country to work in our suppliers’ factories, we increased audits in Malaysia
and Singapore, countries known to be destinations for foreign contract workers.
As a result, suppliers reimbursed $3.3 million in excess foreign contract worker
fees, bringing the total that has been repaid to workers since 2008 to $6.7 million."
Nowhere does it say 3.6 and it looks like it's millions, not billions; Apple also say they made the factories pay it, they didn't pay it themselves.