Editing invoice descripition before invoice gets generated

I've noticed for domain transfer invoice generated adds note '1 Year/s' to end of order description.
Case is sometimes with some domain registrar domain is not being renewed for 1 year.

Would like to remove from invoice description that 1 year/s notification if this domain extension is used for transfer.

1. Client makes an order with transfer to .COM domain. Now lets say if that extension wouldn't renew domain for one year..
2. Client gets invoice for amount 0 USD. Due domain is not renewed. In description is written 'Domain Renewal example.com - 1 Year/s'.
3. Now since domain is not actually renewed, would prefer to remove that 1 Year/s from description line {if} domain name is using in this case extension .COM and order is Transfer.

In language file that is taken from,
$_LANG['orderyears'] = "Year/s";

However in
/public_html/templates/mycustomtemplate
There is no such file that would consist that line which takes from language file that description. Any ideas how to change what I'm expecting to? Whmcs support said it might be possible with action hook, but they had lack of intrest on it.

looked into invoicepdf.tpl aswell but nothing caught my attention that I could change there. Possibly that file is decrypted what I'm looking for.