If a user gave positive feedback to a support ticket, this may be a good moment to ask him for a (hopefully positive) review on Trustpilot (or any other review platform you like).
To do this, you need to edit viewticket.tpl, looking for these lines of code:
<div class="message">
{$reply.message}
{if $reply.id && $reply.admin && $ratingenabled}
<div class="clearfix">
{if $reply.rating}
<div class="rating-done">
{for $rating=1 to 5}
<span class="star{if (5 - $reply.rating) < $rating} active{/if}"></span>
{/for}
<div class="rated">{$LANG.ticketreatinggiven}</div>
</div>
{else}
<div class="rating" ticketid="{$tid}" ticketkey="{$c}" ticketreplyid="{$reply.id}">
<span class="star" rate="5"></span>
<span class="star" rate="4"></span>
<span class="star" rate="3"></span>
<span class="star" rate="2"></span>
<span class="star" rate="1"></span>
</div>
{/if}
</div>
{/if}
</div>
{if $reply.attachments}
And just before {if $reply.attachments} insert the following lines of code:
{if $reply.rating == 5}
<div class="alert alert-success" align="left">{$LANG.tickettrustpilotfeedback}</div>
{/if}
In your language file(s), define the tickettrustpilotfeedback language variable with something like:
$_LANG['tickettrustpilotfeedback'] = "Did you appreciate our service?<br>Please, <a href=\"https://www.trustpilot.com/evaluate/example.com\">rate us on Trustpilot</a> to help us spread the word!";
(change the fake link to example.com with your own link on Trustpilot)
After doing so, when a user will give a 5 stars feedback to any answer from your support, on the ticket page he will see this: