fm 2012 staff problem

Hi, im playing fm 2012, and i recently fired di matteo as my assistant coach but before i could appoint a new assistant coach another coach named El Saka automatically appeared to fill the vacant assistant coach position, problem is i found a better coach than el saka but i cant fire el saka because he is under no contract. i tried to sign el saka officially but the board blocks it saying theres no need for another assistant coach. can someone help me? i cant get rid of el saka and i cant hire a better assistant coach.