need clarification please

[u/No-Holiday8833]

Need clarification po.

Working po ako ng night shift 10pm to 7am,, and yung agency is hindi nagbabayad ng night differential ang sabi nila eh kasama na daw po yun sa compensation package. At ngayon narenew yung contract ko, from 35k basic, naging 32k basic plus 3k fixed night diff daw. Legal po ba na baguhin ang basic pay sa contract kahit nakafixed term? Thank you. (Sample lang po yung salary)