Bug Problem with Medication App (Alarm Code) -For Apple

I am needing to fix a few bugs that have been found in my code. It is in relation to an alarm system on a app which deals with oganisation. some of the problems are: - app crashes if finish date for an item is set in a later month like April - counter resets to zero sometimes - alarm is not scheduled for the correct day - different time zones being a problem - alarm is fired multiple times when scheduled. These bugs will be explained in further detail after the freelancer has proposed a price and signed a NDA to allow for them to know everything about the application. If the build is completed on time and with good communication, the price agreed upon will be paid in full with no problems. This application is created using Xcode and is based for the Apple Apps Store.