How would you have handled this?

Both drinks should have been replaced and an apology by the manager but of course they could be closed down for serving alcohol to a minor so they cannot accept the blame.

This happened to us where a waiter gave my 10 year old my mums malibu. DS thought he had been given an empty glass with ice and poured in his J2O and drank it. DM had just been given a coke, no malibu. DS commented his tasted soapy after a few mouthfuls. We didn't complain, just explained what happened and asked for drinks to be replaced. End of story.

I'd be very disappointed with a cocktail if I couldn't immediately tell it had alcohol in it!

As if that kid didn't know they had alcohol lol

The manager took it away because they realised it had alcohol in and the server had mixed the drinks up, it wasn’t OP reporting it.

If course they should have either replaced your cocktail or removed it from the bill. They can't have it both ways - depriving you of it and billing you for it. Yes a cocktail was "wasted" but their error for serving it to the wrong person.

They should have either replaced the cocktail or deducted the cost from your meal. They are fortunate you didn't report them to whoever enforces alcohol laws in the UK for serving alcohol to a minor.

Good grief wjatva bunch of nasty arrogant people on this thread.... obviously the OP was unhappy paying for a cocktail that she didn't get.....ohhhh and here come the perfect parade to make it allll about you not listening to the 15 yr old even though they told you!
Yes I would have been pssed off about paying for a drink I didn't have or not being given the opportunity to swap....those things aren't cheap! Just leave a review on trip advisor and hopefully they will get back to you or call and ask to speak to the manager not only about the drinks but about the terrible service....you paid for a cocktail and an ice cream! Mention that your glad his business is so great that they can afford to be loosing customers over shoddy service!

We did try it, and really couldn't taste it, it was after a few tries , that yes, we figured out it was in fact alcoholic.

If it took a few tries before you decided there was alcohol in it, how are you so sure you were right?

You could be completely wrong if the alcohol taste is that subtle.

They should have replaced your cocktail. And been very apologetic about serving alcohol to a child! Sounds like the service was crap after they realised their mistake, and I would have been very annoyed too. Mistakes happen, and people understand that, it was rude of them to behave so shoddily after they realised!

Why didn't you take the rest of the cocktail?
I think they should have comped it but they did replace a drink, but I'd have kept the cocktail. You drank the mock tail though so I think it wasn't totally out of order to charge you.
The service was another thing - but I'd have spoken up and asked the waitress for more drinks/dessert, not wait to be asked.

I wouldn't pay for a cocktail I hadn't been given either. She should have taken both drinks away and replaced them with the correct order.

Or knocked a couple of quid off the bill. Crap service and I wouldn't have tipped either

I should say that a new drink was also brought to the table straight away.

OP - you should have had at the very least a replacement cocktail and ideally both drinks replaced.

Surely when you realised you would just swap drinks with each other? I mean it was your own child not some grotty randomer. Why did it need to be taken away at all?

Very similar happened to me recently. I ordered a lager in a chain restaurant, it was the 3rd round of drinks. I drank half of it before I saw the label - 0% lager - I couldn’t tell the difference.
When the server came I mentioned it, got an immediate apology and she said I will take it off the bill. No hesitation, no checking with the manager, which I thought was efficient and fair.

Prob on MN I’d be chastised for not reading the label!

But that is my point. Id have asked for it to be replaced - and expected just one on the bill

You didn't ask for it so they assumed you didn't want it. They probably took is by mistake to whip it away from the child.

Was it a very upmarket restaurant? Because if it was more fun of the mill I do expect to have to ask for what I want, waitservice is not that attentive these days

So did you ask for your cocktail to be replaced? Or did you say nothing and moan when the bill came? Same with ordering dessert. If they start clearing your table and they haven't asked if you want dessert but you want one, you say "we want to order dessert".

None of this is complicated. Just (politely) order what you want.

But if you tried it then you did know. Why did you let them remove it? Or not raise that immediately?

If I order a mojito my tummy is ready to drink a mojito. I don't leave it until the bill and then complain. I'd have resolved it there and then

I don’t understand some of the above replies. If I ordered a cocktail and the server fucked up, gave it to my teenager, then whipped it away and I was still expected to pay for it I’d be raging. The cocktail should have been removed from the bill and a discount given.
I think I’d be OK with the mistake - they’re 15 not four, after all - but if I was a manager and my server had done that I’d take it a lot more seriously. I certainly wouldn’t be so blasé and dismissive.

I can't believe people are surprised you wanted money off. At lears I'd not want to pay for the cocktail.