First change this:
if((amount<100) && (amount<1000000)){
                                     printf("Amount must not be less than 0 or more than P1,000,000!");
                                     getch();
                                     system("cls");
                                     goto one;
                                     }

into this:
if((amount<1000) || (amount>1000000)){
                                     printf("Amount must not be less than P1,000 or more than P1,000,000!");
                                     getch();
                                     system("cls");
                                     goto one;
                                     }