Those limits also do exists somehow in other countries. In France for example it's been a very long time some petrol station say "150 EUR maximum". People are going to say it's not a "real" limit but I did hit it once or twice while going on vacation: 80 liters tank, near empty / car only taking 98 octane fuel (more expensive than 95) / ultra-pricey fuel at petrol stations on the highway (so pricey it's usually cheaper to just get off the highway, fill the tank in a village, and go back to the highway).
At 2.2 EUR / liter, 75 liters is 165 EUR so I was blocked at 150 EUR.
50 liters I definitely cannot fill my car entirely.
The 150€ is a reservation on your debit card before filling up, since the banks or the station doesn't want the credit risk. It's released when the actual sum is booked.
I think it's just what a reasonable "full tank" was a while back.
You can just restart if you need more.