In addition, it sounds as if your company is using the strategy of issuing new contracts to avoid part-time workers being deemed as having accumulated full-time rights through long service and extended hours. As buildersmate says, it is not fair but it is legal. View the bottom line - are you happy to do youor job for the pay you get - and for your own peace of mind ignore what others receive. If you are not happy, your only real alternative is to get another job.