Maybe go to a different Chemist.
When I have been told by the Pharmacist that they can't get my prescribed medication I have rung the Manufacturer to ask if they have stopped producing it. Both times I was told no.
The first time was for my HRT patches and I was told to tell the Pharmacist to call them directly - I got my patches with no problem.
The second time I was told that there was plenty of stock at the wholesalers and to ask the pharmacist if they had tried to order. Before I did that I went to the other chemist where I live and they had my tablets in stock.
Hope you get what you need