Write SQL query to solve given problem: Among the elderlies, state the last name of whose complaint is handled in server YIFAT?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T1.last FROM client AS T1 INNER JOIN callcenterlogs AS T2 ON T1.client_id = T2.`rand client` WHERE T1.age > 65 AND T2.server = 'YIFAT'