devi fare un override della view di default di manufacturer (\components\com_virtuemart\views\manufacturer\tmpl\default.php) e linkare direttamente alla pagina di categoria.
negli ultimi template trovi:
// Manufacturer Elements
$manufacturerIncludedProductsURL = JRoute::_('index.php?option=com_virtuemart&view=category&virtuemart_manufacturer_id=' . $manufacturer->virtuemart_manufacturer_id, FALSE);
$manufacturerURL = JRoute::_('index.php?option=com_virtuemart&view=manufacturer&virtuemart_manufacturer_id=' . $manufacturer->virtuemart_manufacturer_id, FALSE);
$manufacturerImage = $manufacturer->images[0]->displayMediaThumb("",false);
// Show Category ?>
<div class="manufacturer floatleft<?php echo $manufacturerCellWidth . $showVerticalSeparator ?>">
<div class="spacer">
<h2>
<a title="<?php echo $manufacturer->mf_name; ?>" href="<?php echo $manufacturerURL; ?>"><?php echo $manufacturer->mf_name; ?></a>
</h2>
<a title="<?php echo $manufacturer->mf_name; ?>" href="<?php echo $manufacturerURL; ?>"><?php echo $manufacturerImage;?></a>
</div>
</div>
devi sostituire nei links $manufacturerURL con $manufacturerIncludedProductsURL. ovviamente, se esiste già un override, la sintassi usata potrebbe differire anche fortemente, quindi dovrai capire dove e come intervenire.
ciao,
marco