Disappointing service and bad attitude

I decided to treat my kids, thought I would surprise them with movies after doing final school shopping. What a disaster!!! I booked 3 tickets for the 14h15 show and since we were early, took kids for lunch. They hadn't finished their meal had a small container of left over fries and 2 almost finished cool drinks.2 sealed bottles of coke and a packet of chips(for later in the day as we had more things to do after the movies) in my trolley, together with my 3 year old's water bottle. There was also a nappy bag in the trolley. upon entering was told by the attendant that I cannot take anything with me inside. I asked her why and she said that's the rule. No outside food items allowed. I told her that no one will be having anything during the movies as we just had a big lunch, however she refused to accept that and asked that I leave all the items with her. Now seriously, am I supposed to trust her with food items???? My son wanted his water bottle and she allowed that. How do you allow the water bottle in but nothing else? I called for the manager & he said the same as her. After arguing I asked for a refund as I wasn't going to continue, that was another lengthy process with forms