prisoner of azkaban ps2 the dementors help

[jay1900]

can someone plz help im going MAAADDDD!!! ive got to the final scene with harry dragging sirius along the bank and the dementors are after him, they are trying to drag his soul off im firing the spell at them but sirius keeps dying every time im hitting the one thats got him but keep having to restart the scene. i dont know about the demetors flying but the ps2 will be .......straight out the window lol can anyone help plzzzzzz.