You can search invoices through several filters. Within the tag filters -> filter type you can specify the parameter of your search:
<?xml version="1.0" encoding="UTF-8"?>
<envelope>
<header>
<actor>test</actor>
    <user>test</user>
    <password>test</password>
    <version>1.0.0</version>
    <timestamp>20200501170000</timestamp>
</header>
<query type="listall" product="invoice" />
    <filters>
    <filter type="issued" from="" to=""/>
    <filter type="services" from="" to=""/>
    <filter type="customer" code=""/>
</filters>
</query>
</envelope>