Superdrug complaint: Unhelpful Customer service

I placed an order online with superdrug on 20th July. I chose the 30 minutes pick up service. As I placed the order the site said there were no problems and I’d receive an email when to pick up.
I gave this a few hours when I didn’t receive the email I contacted Superdrug Customer service they said my order was pending.
I contacted them again on the 21st several times. They were rude, rushed me and were very unhelpful. They claimed my order was still pending.
I contacted them again on the 22nd eventually I reached a man who was very helpful and called the store. He told me my order is waiting for me there.
When I received my order I am missing an item. And I have not been informed they have not refunded me. No apology nothing. I contacted customer service AGAIN. The man says he will send me the refund.
I am extremely unhappy and outraged with this whole ordeal. It has been extremely stressful and I do not expect to be treated like that by customer service.
I want to make this complaint official. Is this the right route?