Extract coordinates out of xml with xpath and some criterias

i have spent hours of searching for a solution, but now i need your help. Probably you will joking about me, but...anyway. I'd like to fetch the coordinates and maybe some othe information when xpath matches the crtiteria value=bnb

I tried the syntax //Data/value['bnb']/ancestor::Point/coordinates[text()] with no result.

      <Placemark xmlns="">
    <name><![CDATA[Malcesine]]></name>
    <Point>
      <coordinates>10.8103913069,45.7645853643</coordinates>
    </Point>
    <ExtendedData>
      <Data name="tournumber">
        <value>1</value>
      </Data>
      <Data name="guidename">
        <value>Lake Garda</value>
      </Data>
      <Data name="category">
        <value>numeration</value>
      </Data>
      <Data name="category">
        <value>bnb</value>
      </Data>
      <Data name="WayPointNumber">
        <value>3</value>
      </Data>
    </ExtendedData>
  </Placemark>
  <Placemark xmlns="">
    <name><![CDATA[Gelateria Cento per cento]]></name>
    <Point>
      <coordinates>10.8087927103,45.7659774682</coordinates>
    </Point>
    <ExtendedData>
      <Data name="tournumber">
        <value>1</value>
      </Data>
      <Data name="guidename">
        <value>Lake Garda</value>
      </Data>
      <Data name="WayPointNumber">
        <value>3</value>
      </Data>
    </ExtendedData>
  </Placemark>

Thx in advance