My girlfriend and I recently rented a small motorhome from a company in Germany which we had a great journey in. A few days into our trip we noticed that something was damaged/malfunctioning. We were aware that these things would cost between €100-€150 to replace or cheaper to fix. We weren't sure whether it was something we'd broken or something we'd inherited from a previous renter that the company was aware of so we figured we'd just enjoy our trip and see if we got charged from the deposit we had put down as we were more than willing to pay for any damage we'd caused. The company has since witheld almost €500 for the damage. Itemised as more than €400 for the part and then some other items for adminstration fees etc. I expected some kind of mark-up but 3-4 times the part price seems ridiculous to me. Is there any kind of recourse available to us in Germany?
Some further information that may or may not be important. I'm a UK resident/citizen. My girlfriend is an NL resident/citizen. The purchases were made from Dutch bank accounts, no credit cards.