PDO fetch me a fake result

Question

I'm working on a function that compare two price.

I have a table called 'PRODUCT' that has 3 column: ID, REFERENCE, PRICE.

I get a price from a FORM that i will compare with the column PRICE. If the number that i get with the form, is different by PRICE from the table, i want get the REFERENCE. So i work in this way:

$pdo = new PDO ("mysql:host=$hostname;dbname=$dbname", $user, $pass);

    $sql = "SELECT count(1) as NB
    FROM ww_ps_product
    WHERE reference = :reference AND SUBSTR(wholesale_price , 1, INSTR(wholesale_price ,'.')+2)  != :price" ;

    $stmt =  $pdo->prepare($sql);

    $stmt->bindValue(':reference', **$referenza**, PDO::PARAM_STR);
    $stmt->bindValue(':price', **$prezzoAggiornato**);

    $stmt->execute();

    $product = $stmt->fetch(PDO::FETCH_ASSOC);

The value that i get from the form : $referenza is FIN 260482300000 and the $prezzoAggiornato is 6.90 . Normalli, in my $product, i should have 0 but i get 1.

This data are store in DB with the same values:

When i go to compare with my function, i get NB = 1 but that's is impossible. If i check with the same values in phpMyAdmin i get NB = 0.

There is something wrong in my code?