i managed to achieve the responsive scaling i needed
i changed the php in public_html/wp-content/plugins/wallets-exchange/templates/chart.php
from
<div class=”chart-container” style=”width:<?php echo absint( $atts[‘width’] ); ?>px;height:<?php echo absint( $atts[‘height’] ); ?>px;”></div>
to
<div class=”chart-container” style=”width:auto>px;height:<?php echo absint( $atts[‘height’] ); ?>px;”></div>
<?php
i see this works ok