Bug: PrestaShop POST request returns all product attributes

[Cloudio]

Hi, as you read by the title i'm trying to update the catalog of my shop by using the Webservice API

Here's the problem when i send the POST request:

<?xml version="1.0" encoding="UTF-8"?>
<prestashop xmlns:xlink="http://www.w3.org/1999/xlink">
    <product_option_values>
        <product_option_value id="8159" xlink:href="https://www.sciarasouani.it/api/product_option_values/8159"/>
        <product_option_value id="8160" xlink:href="https://www.sciarasouani.it/api/product_option_values/8160"/>
        <product_option_value id="8161" xlink:href="https://www.sciarasouani.it/api/product_option_values/8161"/>
        <product_option_value id="8162" xlink:href="https://www.sciarasouani.it/api/product_option_values/8162"/>
        <product_option_value id="8163" xlink:href="https://www.sciarasouani.it/api/product_option_values/8163"/>
        <product_option_value id="8164" xlink:href="https://www.sciarasouani.it/api/product_option_values/8164"/>
        <product_option_value id="8165" xlink:href="https://www.sciarasouani.it/api/product_option_values/8165"/>
        <product_option_value id="8166" xlink:href="https://www.sciarasouani.it/api/product_option_values/8166"/>
        <product_option_value id="8167" xlink:href="https://www.sciarasouani.it/api/product_option_values/8167"/>
        <product_option_value id="8168" xlink:href="https://www.sciarasouani.it/api/product_option_values/8168"/>
        <product_option_value id="8169" xlink:href="https://www.sciarasouani.it/api/product_option_values/8169"/>
        <product_option_value id="8170" xlink:href="https://www.sciarasouani.it/api/product_option_values/8170"/>
        <product_option_value id="8171" xlink:href="https://www.sciarasouani.it/api/product_option_values/8171"/>
        <product_option_value id="8172" xlink:href="https://www.sciarasouani.it/api/product_option_values/8172"/>
		.  .  .
    </product_option_values>

The URL request looks like this:

https://sciarasouani.it/api/product_option_values?ws_key=API_KEY&Account=API_KEY

and the body of the request like this:

<?xml version="1.0" encoding="UTF-8"?>
<prestashop xmlns:xlink="http://www.w3.org/1999/xlink">
    <product_option_value>
        <id_attribute_group>
           85
        </id_attribute_group>
        <position>
            1
        </position>
        <name>
            <language id="1">
                GUER_64203
            </language>
        </name>
    </product_option_value>
</prestashop>

I've tried to wrap the body params ↑ into CDATA but it gives the same result as if i'm doing a GET request of all product_option_values

Please help me out! Thank you in advance