Recursively search the parsed multidimensional array which came from namespaced XML and return its parent key

I am trying to get the key index based on the value that I am searching in the array. I have the following array:

    [0] => Array
                (
                    [n1:ProductWithTermPricingOptions] => Array
                        (
                            [n1:ProductName] => Customer will provide modem
                            [n1:PricingOptions] => Array
                                (
                                    [n1:Priority] => 600
                                    [n1:PricingOptionCode] => LCTL_SA_MDM_NONE_LCTL:NONE:MODEM:IN:CON:SA:na:na:NONE:NONE:-1:-1:NONE:LCTL:NONE:0:na:NONE:A:PO:na:0:NULL:NULL:NULL
                                    [n1:ProductMonthlyCharge] => $0.00
                                    [n1:PromoMonthlyCharge] => $0.00
                                    [n1:ProductActivationCharge] => $0.00
                                    [n1:ProductActivationChargeDescription] => Array
                                        (
                                        )

                                    [n1:ContractLength] => Array
                                        (
                                        )

                                   
                                        (
                                        )

                                   
                                        (
                                        )

                                    [n1:ProductDisclaimer] => Array
                                        (
                                        )

                                  
                                )

                        )

I need to get the key number where the value "Customer will provide modem" resides in this case it should return number 0 for the key. In other situation it will return a different position. I have tried the following but it returns the key where the value is and not [0]:

public static function searchArrayKeybyValue(array $array, $search) {
    foreach ( new RecursiveIteratorIterator ( new RecursiveArrayIterator ( $array ) ) as $key => $value ) {
        if ($search === $value)
            return $key;
    }
    return "N/A";
}

My goal here is to put this option in the last position of the array.

function array_finder($array, $search, $parent_key = false)
{
   foreach ($array as $local_key => $value) {
      $key = ($parent_key === false) ? $local_key : $parent_key;

      if (is_array($value) and ($subsearch = array_finder($value, $search, $key)) !== false) {
         return $subsearch;
      } elseif ($value == $search) {
         return $key;
      }
   }
   return false;
}
echo array_finder($array, 'Customer will provide modem');