Proper XML multicall

i want to send a multicall to Rtorrent Rpc instead of some singlecalls, therefor i need to know how to format my xml call. At the moment my test xml call looks like that:

("<?xml version=\"1.0\"?><methodCall><methodName>system.multicall</methodName>
    <params><param><value><array><data><value><struct><member><methodName>d.get_name</methodName>
        <params><param><value><string>1A0AF8BB650FEFB64A6F5A800CD2770BD1658D52</string></value></param></params></member></struct></value>
    <value><struct><member><methodName>d.get_bytes_done</methodName>
        <params><param><value><string>1A0AF8BB650FEFB64A6F5A800CD2770BD1658D52</string></value></param></params></member></struct></value>
</param></params></methodCall>");

But i only get this response:

<?xml version="1.0" encoding="UTF-8"?>
<methodResponse>
<fault>
<value><struct>
<member><name>faultCode</name>
<value><i4>-503</i4></value></member>
<member><name>faultString</name>
<value><string>Call XML not a proper XML-RPC call.  Call is not valid XML.  Invalid XML "content".  Problem with token at '&lt;/param&gt;&lt;/params&gt;&lt;/methodCall&gt;...': mismatched tag</string></value></member>
</struct></value>
</fault>
</methodResponse>

For example a working single call looks like that:

    <?xml version=\"1.0\"?><methodCall><methodName>d.get_name</methodName>
<params><param><value><string>1A0AF8BB650FEFB64A6F5A800CD2770BD1658D52</string></value></param></params></methodCall>

the only info i found were these:

system.multicall takes one argument as an array. The array contains one
or more structs with the keys methodName and params. You can add any
number of commands.

Anyone an idea what i`m doing wrong?