What did Amnesty International do to get Guantanamo Bay prison closed?

(i) Amnesty International, an international human rights organisation, collected information on the condition of the prisoners in Guantanamo Bay and reported that prisoners were being tortured in ways that violated the US laws.
(ii) They were being denied the treatment that even prisoners of war must get as per international treaties. Prisoners were not released even after they were officially declared not guilty.
(iii) The UN Secretary General said that the prison in Guantanamo Bay should be closed down. The US government refused to accept these pleas.