There is a line in the insert code that will automatically save the insert id into the session. Line 47 you have:
$InsertQuery->saveInSession("customersID");
Just update that to:
$InsertQuery->saveInSession("svClinetID");
That will save the insert id into the session as $_SESSION['svClinetID']
You don't have to do this manually. (Delete the code you added on lines 27-30. Even if it had the correct syntax it wouldn't work because it is above the insert code. You can't get the insert id before the insert takes place.