在条件下更改foreach中的数组值

I have a resulting array like this:

array (size=3)
  0 => 
    array (size=3)
      'service' => string 'Blood Tranfusion' (length=16)
      'unit' => string '1' (length=1)
      'service_charges' => string '170' (length=3)
  1 => 
    array (size=3)
      'service' => string 'Nebulization' (length=12)
      'unit' => string '2' (length=1)
      'service_charges' => string '100' (length=3)
  2 => 
    array (size=3)
      'service' => string 'Service Charge' (length=14)
      'unit' => string '4' (length=1)
      'service_charges' => string '200' (length=3)
 3 => 
    array (size=3)
      'service' => string 'Registration Charge' (length=19)
      'unit' => string '4' (length=1)
      'service_charges' => string '200' (length=3)

I am outputting the result from these array is like this:

foreach($services as  $service){ 

     echo "<tr><td>";  
     echo $service['service'];     
     echo "</td><td>";  
     echo number_format($service['service_charges'],2);
     echo "</td><td>";
     $chargeable_service_unit=0;
     $service_unit =$service['unit'];

     if ($service_unit < $model->packagedays  ){         
         $chargeable_service_unit = 0;

     }else{
        $chargeable_service_unit = $service_unit - $model->packagedays;         
     }
     echo $chargeable_service_unit;
     echo "</td><td>";  
     $service_charges_total = (($service['service_charges'])*($chargeable_service_unit));
     $serviceTotalAmount += $service_charges_total;

     $service_charges_total_amount+=$service_charges_total;
     echo number_format($service_charges_total,2);     
     echo "</td></tr>"; 

   }

Now What I want is say the package days is 4 and array result is like this

Blood Tranfusion =1
Nebulization = 2
Service Charge = 5

then the final result should be

Blood Transfusion = 1
Nebulization = 2
Service Charge = 1

if service charge is 4 or less then 4 then service charge =0

I think It is little complex. I am ready to provide more detail if needed.

Run through the array and reassign like this:

$i = 0;
foreach ($services as $k => $v) {
    if ( $services[$i]['service'] === 'Service Charge' || 'Registration Charge' ) {
        $services[$i]['unit'] = '0';
    }

    ++$i;
}