Adding an array of structs into a file in c - c

Question

I have a code where I am able to add my struct array to a file, but am unable to continue adding contacts to my struct array like I should.
Here are my variables:
struct contact { // Data structure that holds contact information
char FirstName[10]; // Array for first name
char LastName[10]; // Array for last name
int PhoneNum; // Phone number
};
int Choice = 0;
int n = 0;
int size = 1;
struct contact *con = (struct contact *)malloc(size * sizeof(struct contact));
int a = 0;
int b = 0;
int SortChoice = 0;
int iRandNum = 0;
int Valid = 0;
char temp[10];
int tempNum = 0;
char File[20];
int status = 0;
FILE *pRead;
FILE *pWrite;
Here is the add contact part:
if (n == size)
{
size = size * 2;
con = (struct contact*)realloc(con, size * sizeof(struct contact));
}
// Records the information given into the structure
printf("\nYou chose to add a contact.");
printf("\nFirst name: ");
scanf("%s", con[n].FirstName);
printf("\nLast name: ");
scanf("%s", con[n].LastName);
printf("\nPhone number (Numbers only): ");
scanf("%d", &con[n].PhoneNum);
printf("\nRecord added to the phone book.");
// Prints out the given information
printf("\n\nNew contact:");
printf("\nFirst name: %s", con[n].FirstName);
printf("\nLast name: %s", con[n].LastName);
printf("\nPhone number: %d", con[n].PhoneNum);
printf("\nContact number is %d", n);
printf("\n");
n += 1;
And here is the file part:
printf("\nYou chose to store all contacts to a file.");
if (status == 0){
printf("\nWhat would you like to name your file?\n");
scanf("%s", &File);
printf("\nFile name is %s", File);
pWrite = fopen(File, "w");
if (pWrite == 0){
printf("\nFile not opened");
}
else {
for (a = 0; a < n; a++){
fwrite(&con[a], sizeof(struct contact), 1, pWrite);
}
fclose(pWrite);
pRead =fopen(File, "r");
printf("\n\nContacts added to %s", File);
printf("\n\nContacts in file:\n");
while (fread(&con[a], sizeof(struct contact),1, pRead)){
printf("\n");
printf("\nFirst name: %s", con[a].FirstName);
printf("\nLast name: %s", con[a].LastName);
printf("\nPhone number: %d", con[a].PhoneNum);
printf("\n");
}
fclose(pRead);
}
}
If you guys can figure out where I've gone wrong, and potentially why I can't continue to access the file I created that would be great. Thanks