We appreciate Shiko's willingness to appologize for the predicament we faced. According to the description, the apartment can host up to five adults and there is not cost for additional guest. I will suggest the following:
1. Make it express that guest are obligated to inform the host on who sleeps over in the house. Some hosts do this.
2. Be consistent. Once you extend an offer, make sure to keep it. Travellers often make advance plans and any abrupt change turns everything upside down.
3. Have one person for the guests to correspond with. We never knew Lucy and we shouldn't have had to. When multiple people are involved ina communication channel, a lot of information is lost in translation and this is never good for the host or the guest.
4. Your apartment is great. Use better technology to better conserve energy and safe the hosts responsibility of switching a water heater on and off. A temperature switch on the water heater can achieve this by keeping the heater off when the water is at set temperature.