The car rental company is quite good.

We rented two cars at the same time and parked them together. One car was charged over 500 RMB for parking, while the other had no parking fee but was charged 72 euros for cleaning.

Patience

Had to wait in line for over half an hour to pick up the car, and returning it took about 40 minutes too. Plan ahead if you have a flight to catch.

The price didn't match what was advertised on the website. The site mentioned a charge of 4.8 euros per day for crossing the border. We only needed the car for two days in Montenegro but were told to pay a maximum charge of 48 euros for ten days (even though we were renting the car for only eight days). The reason given was that they couldn't know how many days we would be abroad, despite entry and exit records clearly showing this. It felt like an overcharge.