I have added a new user group called driver. It should be allowed to create and edit contact of customer type but should not be allowed to delete it. I have tried to restrict this group using ACL by allowing only Read, Create and Write permissions but it's not working. It can still delete contacts.

<record id="group_rr_driver" model="res.groups">

        <field name="name">Driver</field>

        <field name="category_id" ref="module_rr_helpdesk_category"/>

        <field name="comment">Comments.</field>

</record>

Thanks in advance for your help! :)