As this is a Postpaid Plan, you'll have to pay the basic monthly fee whether you use, don't use, or the line's barred, since it's rightfully still your line unless you ask to terminate it.

I'd advise you to make the payment as soon as you can (or get it terminated, presuming there's no contract), otherwise you'll end up seeing another RM90 (+GST?) added to this new outstanding balance.