If it's in the contract that you don't allow make-up tests, then students have no basis for a complaint against you when you don't allow them a make-up test.
Hadii laga wada xaajoon waayo sababta dhalisay cambaaraynta ayaa  qofka aad cambaaraynaysaa helaynin fursad uu kugu waydiiyo suaalo, dareemayaana niyad xumo.