When you complete a collection request it -seems- to give you the option to 'amend' but it does not allow you to add any more parcels, doing so you have do do everything again from scratch. Streamlining this edit process, so extras can be added or removed without having to start again. Being able to cancel any right up until the point of collection (unless it is the only one, as this would, of course, affect the postperson's route and waste time). Or allow a refund for any 'unavailable' on the day if there has been an error.