I Disputed a debit card transaction and I've been told I've lost the dispute

Ok, so I go to sleep and wake up to a flurry of "scam" accusations. If you want the full story, with dates, I can give that.

22/09/2016 - I go to withdraw 300 euros from my bank, at this point I have been on holiday for 9 days, all inclusive, this is my tenth day and we have decided to use my money I've saved throughout the holiday (because, you know, people actually can save money they intend to use for a further date, we've known about the holiday for 7 months after all) and treat my kids to some go karting and a trip to a theme park before we go home. I get an option on screen for Direct currency conversion, I choose the option to give the transaction in Euros instead of GBP. It asks me if I want a receipt with the transaction, I choose yes. This is at an ATM in the town, the bank is "Banca March".

The ATM is taking some time, It returns my card first, Then surprisingly I get my receipt second. Then the draw opens and is supposed to be holding 300 euros, it isnt. I bend down to look and see if they are stuck in the machine, they aren't. The screen reads "Please Wait" The draw opens again, theres a loud whirring noise and I do the same thing, by this point I'm panicking, a message flashes up on the screen, too fast to read, then the machine returns to the "Please insert card screen". My grandfather, fiancee, kids and myself are distraught. The kids wont be doing what we've spent the day preparing for. I make sure no one else uses the machine whilst I phone my bank - I spend 10 minutes on hold and then I go through the process of what was said earlier about lodging a dispute. This takes roughly 10 minutes.

After the phonecall, I go on google maps (I have free data abroad on 3 network) and find a number for Banca March, I call them and explain what has happened, this takes roughly 5 minutes. The person on the end of phone assures me its common and says to get it touch with my bank but it should be automatically refunded within 2-3 days. I'm feeling a bit better now.
By this time, I have nothing to lose. I wonder if it will spit my money out, if somehow it may have got jammed in the machine. Being that no one else has used the machine, I figure I will use my overdraft and withdraw 20 euros, because that is the lowest note it will dispense. I have nothing left to lose, I'll need a taxi back to the apartment anyways. That withdrawal is successful. I'm perplexed. We return back in the taxi.

23/09/2016 - My bank statement online shows that the withdrawal of 300 euros has been debited and has passed the pending stage. I proceed to call my bank and organise the dispute as fast as I can. It takes about 40 minutes as the lady is confused by the change in amounts that was previously stated (it was originally £258.94 but is now £258.33 due to currency rates changing) eventually we get there. After the call, my mother phones and offers to loan me the money. I agree. holiday proceeds as normal, I have happy children again.

I arrive home on the 27th in the early hours. When I wake I check my bank balance - success, you have been refunded the money. I pay my mother back. Everything is normal in my life.

On the 5th October my family and I go to visit relatives across the country, were staying for 10 days. We return home yesterday and I find a letter dated the 4th October that states the bank is re-debiting my account and provides a log of banca march's ATM records. How many people have missed a letter because they have other things going on in their life? Does this make me a liar? Or this a scam?

Sorry if I seem a bit angry or annoyed, I can understand that this may ring alarm bells since there seems to be scam posts going around, but this has caught me off guard. Being accused of being a liar is a pretty crap feeling.

At the time, I never approached the ATM with the thought of "this is going to steal my money, better take photos". It's all good in hindsight, but I had two kids who were crying and generally making quite the scene about this while my partner tried her best to calm them down, an 80 year old grandfather who was needing somewhere to sit down and a lady in my ear telling me there was nothing she could do until the payment had passed a certain stage. I was stressed and upset, heaven forbid it happen to anyone who is not expecting something like this to happen and actually forget to take photos of the bloody machine. I never returned to it, but strangely enough, when I went to the ATM nearer the bus stop after my mother loaned me money, I took a video! Because, you know, I expected it after a terrible experience previously!

I will get in touch with a local bar that was close to the ATM in hopes that they have CCTV outside. There is also a restaurant I will try. I will escalate this to a complaint with my bank. Thanks for the genuine advice from people who answered.