Cashier - Anonymous employee IGA Employee Review

Was promised a raise when I turned 18, never received it. Even though I had been there the longest of all my friends, they all were given manager positions before me. When I went away to college I still wanted to keep my job for when I returned for breaks. Before I came home I always let them know so I could be put on the schedule. From August-December they never worked me when I came home. In December I received a letter from the corporation asking why I quit?