Weird change rates for 2 transactions the same day

I used for the first time a Revolut Card during 3 weeks in South Korea and Bali.
During this time, I had 2 problems with change rates.
The average rate in Bali is around 15.600 Rp for 1€.
For 2 transactions, (1 on ATM and 1 in an hotel), the change rate was 10.924 Rp for 1€, coming back to a normal rate the same day (08/17/2017) for my third transcaction.
I had any other such problems during my travel but are you able to explain it and, I hope, to correct it ?
Thank you

We do use a live rate that adjusts every second. However please contact us in the in-app support and we can always look into a specific transaction for you!

@larysa.stachowicz - Although what you say is true, it doesn’t explain why your EUR/IDR rate should spike downwards by 30% intraday on one day in August, when EUR/IDR has traded between around 15,300 and 15,800 during the whole of August.

Thanks for your answers Larysa.
I chatted with the support 2 days ago. They confirmed that, during perhaps 3 hours, the exchange rates provided by the company who provide it to you was false (in my case).
It seems that it was the first time they saw this situation.
The support refunded me the difference between the day rate and the false used on both my card and the card of my wife.
So, for me, everything is now ok. But I think that someone need to analize this problem on your side to avoid that this problem reproduce in the futrure.