I haven't tested whether this matches your logic, but it should be close, anyway:

sub body { ... your code ...}

SWITCH: {
    body, last SWITCH if $wrongDateFlag and $#ARGV >= 2;
    body, last SWITCH if not $wrongDateFlag and $#ARGV >=2 and $oneDay
+Flag == -1
;
    body, last SWITCH if not $wrongDateFlag and $#ARGV >=1 and $oneDay
+Flag >= 0;
    $felloff == 1;
}
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UPDATE:

I forgot $#ARGV returns one less than scalar @ARGV so I fixed that. Some would probably fault me for using a switch statement where each path calls the same code but I like the resulting look. Cleaner might be.

sub body { ... your code ...}

body if $wrongDateFlag and $#ARGV >= 2
        or not $wrongDateFlag and $#ARGV >=2 
        or not $wrongDateFlag and $#ARGV >=1 and $oneDayFlag >= 0;
[download]

UPDATE:

removed some vestigial semicolons.