I want my shopping free

I went to pay for my stuff at the till when the till rang and it sed I have won my trolley free next min the manger comes and tells the cashier the promo is over how can it be over when. The till clear rang ***** came out instead over rides my purchase n gives me a shopping back bull**** I want my shopping free it clearly when u win u're trolley free everything u purchased is free are they keeping it for themselves or are we fools ****med by pick n pay