advice needed please

[graffi]

my shift manager has changed my duty forcefully(not hours just content) at the end of my old duty i had 12mins time bonus (i belive this time bonus was an old bonus scheme not all offices have it but ours still has, we go home 12mins early))my manager has taken 7mins time bonus off my leaving me with 5mins saying its duty content so he can do this and quoting discrimination because others dont have it(every vacant duty loses time bonus before been advertised)ive put a grievance in yesturday but am p***ed off ,i know its only 7mins but its the principle any advice would be greatfully received thanks

[oldrope]

in our MC we have a 10 min time bonus. it used to be at the end of our shift but got chanegd to the start cart remember why but it left a bad tast