Disappointed customer, missing items

Earlier today (30/03)my sister in law placed an order at your Belgravia branch, we collected the order and because we trusted the staff we did not check the order as the place was packed also and we needed to get to our destination before Iftaar time, only then when we checked we found that our order had quite a few missing items which was paid for. I'm quite disappointed and upset as we were too far away to come back and query our order. I understand they were busy but staff needs to be trained for the busiest of periods. It will probably be a long while before I trust going back there