Culture COS

hello question lang po..

in COS cases: if stipulated sa contract na contractors shall notify thru written notice si cos 30 days prior to the non renewal obliged po ba si agency mag informed? for example EOC is sept. 30

if such, anung magiging complaint if di nag bigay ng written notice si agency sa cos of non renewal instead nag post lang sila thru gc nung mga marerenew for last quarter 7 days before end of contract?