change the hight attribute for the following css:
form.Sidebar_quickinquiry textarea.formTextarea_Medium {
background-color:#fff;
color:#000;
padding:4px 4px 4px 4px;
-webkit-border-radius:2px;
-moz-border-radius:2px;
width:215px;
height:150px;
white-space:pre;
overflow:auto;
margin:0;
border-style:solid;
border-width:1px;
border-radius:2px;
border-color:#cfcfcf;
}
in the webassist/forms/fd_sidebar_quickinquiry.css file.