I agree with RAPC I have always cancelled in such situations and then done a new booking however I have a fairly significant balance with VS (that I am trying to burn down given the ongoing negative changes) so if the points aren't returned immediately it doesn't prevent me from making a new booking. In fact I usually make the new booking first and then cancel the old (just so I know it isn't phantom space). But if you don't have spare points then the way you did it is probably what I'd do. All that said I have never had the points not return immediately when calling in.