Working for Asda - Avis employé Employé (anonyme) ASDA

I've been with the company some time and still do not have the same hours week to week or a contract. I am given roughly 3 days notice on my shifts. This has made booking days off almost impossible. I am not allowed water and have been made to go hours without a toilet/water break, even when ill. There are a lot of members of staff that do not contribute to the team and constantly slack off, but due to their lengthy time with the company are treated far better than the newer staff members. I feel as though I am treated unfairly on a very regular basis and hope to find a new job away from this company soon.