How to recover salary if tussle between 2 companies on who will pay

you work for an organization say 'X' your job profile is to train people under 'X' and associated organization of X say 'Y'. You get hired by X in january and start training people, working on promoting X, getting related material printed, try to get contacts etc. Now Y starts its training in February and pays half of the discussed amount to X in the beginning of March. X pays you for February and refuses to pay you for January stating that you were hired in anticipation of the offer from Y which was supposed to start in Jan but instead started in Feb. You quit working for X after completion of 3 months in April and the second half of the amount from Y gets transferred to X. Working for 3 months for X you only get salary for 1 month. Now who is right who is wrong and what further steps should be taken...?