Que se puede hacer para corregir los errores del siguiente programa

En base al siguiente codigotngo que agregarle 3 funciones más:

1. Que me permita guardar depósitos y retiros

2. Que me deje actualizar los datos de la cuenta ya tomando en cuenta los depósitos y retiros

3. Que presente en un archivo txt el historial de las cuentas si hubo depósitos y retiros yel saldo actual

include <stdio.h>
#include <conio.h>
#include <stdlib.h>

/*Definicion de la estructura clientData */
struct clientData {
int acctNum;
char lastName [15];
char firstName [10];
double balance;
}; /* Fin de la estructura */

/* Prototipos */
int enterChoice (void);
void textFile ( FILE *readPtr );
void updateRecord ( FILE *fPtr );
void newRecord ( FILE *fPtr );
void deleteRecord ( FILE *fPtr );
void transactions ( FILE *fPtr );

int main ()
{
FILE *cfPtr; /* */
int choice;

if ( (cfPtr = fopen( "credit.dat", "rb+" ) ) ==NULL) {
printf("File could not be opened.\n");
}
else {

while( ( choice = enterChoice() ) != 5) {

switch ( choice ) {

case 1:
textFile( cfPtr );
break;

case 2:
updateRecord( cfPtr );
break;

case 3:
newRecord( cfPtr );
break;

case 4:
deleteRecord( cfPtr );
break;
default:

printf("Incorrect choice \n");
break;
}
}
fclose( cfPtr );
}
return 0;
}

/* */
void textFile( FILE *readPtr )
{
FILE *writePtr;

struct clientData client = {0, "", "", 0.0};

if( ( writePtr = fopen("accounts.txt", "w") ) ==NULL) {
printf("File could not be opened.\n");
}
else {
rewind( readPtr );
fprintf( writePtr, "%-6s%-16s%-11s%10s\n",
"Acct", "Last Name", "First Name", "Balance");

while( ! Feof( readPtr ) ) {
fread( &client, sizeof( struct clientData ), 1, readPtr );

if ( client.acctNum !=0 ) {
fprintf( writePtr, "%-6d%-16s%-11s%10.2f\n",
client.acctNum, client.lastName,
client.firstName, client.balance );
}
}
fclose( writePtr );
}
}

/* */
void updateRecord( FILE *fPtr )
{
int account;
double transaction;

struct clientData client = { 0, "", "", 0.0 };

printf("Enter account to update (1-100) : ");
scanf("%d", &account);

fseek( fPtr, ( account - 1) * sizeof( struct clientData ),
SEEK_SET );

fread( &client, sizeof ( struct clientData), 1, fPtr );

if( client.acctNum == 0) {
printf("Acount #%d has no information.\n", account);
}
else {
printf( "%-6d%-16s%-11s%10.2f\n\n",
client.acctNum, client.lastName,
client.firstName, client.balance );

printf("Enter charge (+) or payment (-) : ");
scanf("%lf", &transaction);
client.balance +=transaction; /* */

printf( "%-6d%-16s%-11s%10.2f\n",
client.acctNum, client.lastName,
client.firstName, client.balance );

fseek( fPtr, ( account - 1) * sizeof( struct clientData),
SEEK_SET );

fwrite( &client, sizeof( struct clientData), 1, fPtr );
}
}

void deleteRecord( FILE *fPtr)
{
struct clientData client;

struct clientData blankClient = { 0, "", "", 0 };

int accountNum;

printf("Enter account number to delete (1-100): ");
scanf("%d", &accountNum);

fseek( fPtr, (accountNum - 1) * sizeof( struct clientData),
SEEK_SET);

fread( &client, sizeof( struct clientData ), 1, fPtr);

if (client.acctNum == 0) {
printf("Account %d does not exist.\n", accountNum);
}
else {

fseek( fPtr, ( accountNum -1) * sizeof(struct clientData),
SEEK_SET );
fwrite( &blankClient,
sizeof(struct clientData), 1, fPtr );
}
}

void newRecord( FILE *fPtr )
{
struct clientData client = { 0, "", "", 0.0 };
int accountNum;

printf("Enter new account number (1-100): ");
scanf("%d", &accountNum);

fseek( fPtr, (accountNum -1) * sizeof( struct clientData ),
SEEK_SET );

fread( &client, sizeof( struct clientData), 1, fPtr);

if( client.acctNum !=0 ) {
printf( "Account #%d already contains information.\n",
client.acctNum);
}
else {
printf("Enter lastname, firstname, balance\n? ");
scanf( "%s%s%lf", &client.lastName, &client.firstName,
&client.balance );

client.acctNum = accountNum;

fseek( fPtr, ( client.acctNum - 1 ) *
sizeof( struct clientData ), SEEK_SET );

fwrite( &client,
sizeof( struct clientData), 1, fPtr );
}
}

int menuChoice;

printf( "\n Enter your choice\n"
"1 - store a formatted text file of acounts called\n"
" \"accounts.txt\" for printing\n"
"2 - update an account\n"
"3 - add a new account\n"
"4 - delete an account\n"
"5- end program\n? " );
scanf( "%d", &menuChoice);
return menuChoice;
}