I had similar on a ferry once Cellar - there was a little cafe in the corner, and as I wanted to buy sandwiches and crisps and drinks for the family I walked round the counter from the end where the trays were, past the refrigerated displays, taking what I wanted and then round to the till.
When I got to the till there was what turned out to be a queue going in the opposite direction, along a wall, but it just looked like a big gaggle of people, so when the person being served left with their food, I stepped up to pay.
"Scuse me love, queues this way!" Gets shouted at me. I tried to reason that I'd followed the logical way around, but he'd decided to make his own queue as he "only wanted a tea and didn't need to look at the food" and others had joined behind him. I refused to budge and told the server they needed a sign to make it clear which way the queue was. By this point bloke and his family are swearing at me and calling me rude. I walked off with my food and promptly cried my eyes out. As I left the server apologised to the bloke for his wait! No apology for the abuse I got. I know it was because she didn't want him to kick off at her, but really?!
Now I'd just tell him to make a fucking sign if it was so important to him.
A few weeks ago returning home from holiday a family obviously wanted to check in quickly and barged me out of the way as the line was moving up (it was free flowing and moving quick at this point as we'd just arrived and check in just opened). I'd already been split from the rest of my family by another family of queue jumpers (because of course I'm struggling with DS case as well as my own whilst he skips ahead and everyone else only has 1 case, yay Mums!), so I just unclipped the ribbon barrier, stepped through, clipped it behind me and called out loudly as the rest of my family joined me 'We got split up because people barged me out of the way! Never mind, sorted now" tinkley laugh.