Clear data from a PHP loop

I manage to erase data but only when there are 2 things in the loop. When there are more than 2 it only deletes 2 in 2 and I do not know why.

<?php
session_start();


if(isset($_GET['p'])){
$_SESSION['producto'][$_SESSION['contador']] = $_GET['p']; 
$_SESSION['contador']++;


}

if (isset($_GET['c'])){
$_SESSION['cantidad'][$_SESSION['contador']] = $_GET['c'];
}

include '../conexion/server.php';
$suma = 0;
for ($i=0; $i < $_SESSION['contador']; ++$i){
//echo "producto:".$_SESSION['producto'][$i]."-".$_GET['c'][$i]."<br>";

    $query = mysqli_query($conect,'SELECT * FROM Productos WHERE 
    id='.$_SESSION['producto'][$i].'');

    while ($fila = mysqli_fetch_array($query)) {


        $cab = $_SESSION['cantidad'][$i+1];
        $total = $fila['Precio']*$cab;
            echo '<tr>';
            echo '<td>'.$fila['Nombre'].'</td>';
            echo'<td></td>';
            echo '<center><td>';
            echo '<center><input type=number name=ja class="las ma" 
   value='.$cab.'></center>';
            echo '</td></center>';
            echo '<td>$'.$fila['Precio'].'</td>';
            echo '<td>'.$i.'</td>';
            echo '<td>$'.number_format($total,2).'</td>';
            echo '<td>';
            echo '<input type=hidden value='.$_SESSION['contador'].' 
            class=jk>';
            echo '<a href=functions/checkout.php?a='.$i.' 
            class=borrar>Borrar</a>';

            echo '</td>';
            echo '</tr>';

                $suma += $total;                                            
    }

    if(isset($_GET['a'])){

                    unset($_SESSION['producto'][$_GET['a']]);

                    $_SESSION["producto"] = 
  array_values($_SESSION["producto"]);

                        $_SESSION['contador'] -=1;
                }
 }

 echo '<tr><th colspan="5">Total</th><th 
colspan="2">$'.number_format($suma,2).'</th></tr>';
mysqli_close($conect);

 ?>