backup and open \include\client\open.inc.php
FIND:
<tr>
<th width="20%">Full Name:</th>
<td>
<?if ($thisclient && ($name=$thisclient->getName())) {
?>
<input type="hidden" name="name" value="<?=$name?>"><?=$name?>
<?}else {?>
<input type="text" name="name" size="25" value="<?=$info?>">
<?}?>
<font class="error">* <?=$errors?></font>
</td>
</tr>
REPLACE WITH:
<tr>
<th width="20%">Full Name:</th>
<td>
<?if ($thisclient && ($name=$thisclient->getName())) {
?>
<input type="hidden" name="name" value="<?=$name?>"><?=$name?>
<?}else {?>
<input type="text" name="name" size="25" value="<?=$info?>">
<?}?>
<font class="error">* <?=$errors?></font>
</td>
<th width="20%">Select Company:</th>
<td width="20%">
<select size="1" name="D1">
<option>option1</option>
<option>option2</option>
</select>
</td>
</tr>
FIND:
<tr>
<th nowrap >Email Address:</th>
<td>
<?if ($thisclient && ($email=$thisclient->getEmail())) {
?>
<input type="hidden" name="email" size="25" value="<?=$email?>"><?=$email?>
<?}else {?>
<input type="text" name="email" size="25" value="<?=$info?>">
<?}?>
<font class="error">* <?=$errors?></font>
</td>
</tr>
REPLACE WITH:
<tr>
<th nowrap >Email Address:</th>
<td>
<?if ($thisclient && ($email=$thisclient->getEmail())) {
?>
<input type="hidden" name="email" size="25" value="<?=$email?>"><?=$email?>
<?}else {?>
<input type="text" name="email" size="25" value="<?=$info?>">
<?}?>
<font class="error">* <?=$errors?></font>
</td>
<th width="20%">Select Support:</th>
<td width="20%">
<select size="1" name="D1">
<option>option1</option>
<option>option2</option>
</select>
</td>
</tr>
EDIT the dropdown to suit your needs :)