There has been a manufacturing problem with both the branded 'Xenical' 120mg and generic orlistat 120mg capsules since the beginning of this year. Supplies were first expected in February, then pushed back to March, then again to April and now again to May.
If you cannot wait for the supply chain to be reistablished, it is possible to buy 'Alli' capsules (orlistat 60mg) from your local pharmacy. They are however expensive to buy.
If it was me, I would wait for the manufacturers delay to end and get your prescription dispensed then.