diff --git a/LangLang/Domain/Models/Course.cs b/LangLang/Domain/Models/Course.cs
index c37037d..88340fb 100644
--- a/LangLang/Domain/Models/Course.cs
+++ b/LangLang/Domain/Models/Course.cs
@@ -124,7 +124,7 @@ public override string ToString()
             {
                 sbDays.Remove(sbDays.Length - 1, 1);
             }
-            return string.Join("|", new object[] { Id, TutorId, Language, Level.ToString(), NumberOfWeeks, sbDays.ToString(), Online, NumberOfStudents, MaxStudents, StartDateTime.ToString(), CreatedByDirector, Modifiable, GratitudeEmailSent, CreatedAt});
+            return string.Join("|", new object[] { Id, TutorId, Language, Level.ToString(), NumberOfWeeks, sbDays.ToString(), Online, NumberOfStudents, MaxStudents, StartDateTime.ToString(Constants.DATE_TIME_FORMAT), CreatedByDirector, Modifiable, GratitudeEmailSent, CreatedAt.ToString(Constants.DATE_TIME_FORMAT) });
         }
 
         public string ToPdfString()
diff --git a/LangLang/Repositories/CourseRepository.cs b/LangLang/Repositories/CourseRepository.cs
index 04360a4..328697b 100644
--- a/LangLang/Repositories/CourseRepository.cs
+++ b/LangLang/Repositories/CourseRepository.cs
@@ -69,7 +69,7 @@ public Dictionary<int, Course> Load()
                 bool createdByDirector = bool.Parse(tokens[10]);
                 bool modifiable = bool.Parse(tokens[11]);
                 bool gratitudeEmailSent = bool.Parse(tokens[12]);
-                DateTime createdAt = DateTime.Parse(tokens[13]);
+                DateTime createdAt = DateTime.ParseExact(tokens[13], Constants.DATE_TIME_FORMAT, null);
                 var course = new Course(id, tutorId, language, level, numOfWeeks, daysOfWeek, online, numOfStud, maxStud, startDateTime, createdByDirector, modifiable, gratitudeEmailSent, createdAt);
 
                 courses.Add(course.Id, course);
diff --git a/LangLang/Repositories/ExamSlotRepository.cs b/LangLang/Repositories/ExamSlotRepository.cs
index 8a4425b..3d9caf7 100644
--- a/LangLang/Repositories/ExamSlotRepository.cs
+++ b/LangLang/Repositories/ExamSlotRepository.cs
@@ -95,7 +95,8 @@ public void Save()
                     exam.Applicants.ToString(),
                     exam.Modifiable.ToString(),
                     exam.ResultsGenerated.ToString(),
-                    exam.ExamineesNotified.ToString());
+                    exam.ExamineesNotified.ToString(),
+                    exam.CreatedAt.ToString(Constants.DATE_TIME_FORMAT));
         });
 
             File.WriteAllLines(_filePath, lines);
@@ -123,8 +124,8 @@ public Dictionary<int, ExamSlot> Load()
                 bool modifiable = bool.Parse(values[8]);
                 bool resultsGenerated = bool.Parse(values[9]);
                 bool examineesNotified = bool.Parse(values[10]);
-                DateTime createdAt = DateTime.Parse(values[11]);
-                
+                DateTime createdAt = DateTime.ParseExact(values[11], Constants.DATE_TIME_FORMAT, null);
+
                 ExamSlot exam = new ExamSlot(id, language, level, timeSlot, maxStudents, tutorId, applicants, modifiable, resultsGenerated, examineesNotified, createdAt);
                 exams.Add(id, exam);
 
diff --git a/LangLang/Repositories/PenaltyPointRepository.cs b/LangLang/Repositories/PenaltyPointRepository.cs
index 4ed54e6..7f07767 100644
--- a/LangLang/Repositories/PenaltyPointRepository.cs
+++ b/LangLang/Repositories/PenaltyPointRepository.cs
@@ -76,7 +76,7 @@ public void Save()
                     point.StudentId.ToString(),
                     point.TutorId.ToString(),
                     point.CourseId.ToString(),
-                    point.Date.ToString());
+                    point.Date.ToString(Constants.DATE_TIME_FORMAT));
             });
 
             File.WriteAllLines(_filePath, lines);
@@ -98,7 +98,7 @@ public Dictionary<int, PenaltyPoint> Load()
                 int studentId = int.Parse(values[1]);
                 int tutorId = int.Parse(values[2]);
                 int courseId = int.Parse(values[3]);
-                DateTime date = DateTime.Parse(values[4]);
+                DateTime date = DateTime.ParseExact(values[4], Constants.DATE_TIME_FORMAT, null);
                 PenaltyPoint point = new PenaltyPoint( id, studentId, tutorId, courseId, date);
                 points.Add(point.Id, point);