How do I update the filters on the existing subscription

Hi,

I already have a servicebus namespace/topic/subscription created

But now I want to add the filter on the subscription without deleting the subscription

so my code looks like this in powershell

=[Microsoft.ServiceBus.Messaging.MessagingFactory]::CreateFromConnectionString($sbr.ConnectionString)

if(!$NamespaceManager.SubscriptionExists($topic,$t_subscription)) {

$subscriptionClient=$messagingFactory.CreateSubscriptionClient($topic,$t_subscription)

else

#$subscriptionClient =$messagingFactory.GetSubscriptionClient($topic,$t_subscription)

the line #$subscriptionClient =$messagingFactory.GetSubscriptionClient($topic,$t_subscription)

is worng because the$messagingFactory.GetSubscriptionClient($topic,$t_subscription) method does not exist. Can you point me to right call I need to make to retrieve existing clientsubscriptions to update

thanks