cant turn off Conditional call forwarding

im missing jobs becurse of this, and im getting sick of it, it wont even turn off "always forward", i try ring 901, and it ends the call, its says its disabled but all it give me is a option to put in another number,i dont have another number,so i turn to you guys and nothing works, im at a stage where ive throw the phone against the wall its that bad,the (busy,unanswered,and unreachable can stay on thats fine,but come on let me get access to my mail,bring back the good old nokia 3310 i had no issuses what so ever,