Cannot control thermostats individually
**Describe the bug**
Its not possible to control each thermostat individually. If I turn off/on or on one device, all other devices are synched and do the same.

**To Reproduce**
My Config:
`{
            "platform": "FRITZ!Box",
            "name": "My FRITZ!Box",
            "username": "admin",
            "password": "xxxxxx",
            "url": "http://192.168.78.1",
            "interval": 60,
            "concurrent": true,
            "devices": {
                "099950478222": {
                    "ContactSensor": false
                },
                "099950476223": {
                    "ContactSensor": false
                },
                "099950477224": {
                    "ContactSensor": false
                }
            }
        },`

**Expected behavior**
Every device should be turned on & off separately, not auto-synched with other devices

**Screenshots**
![thermostat](https://user-images.githubusercontent.com/12933672/95221136-6d7a9a00-07f7-11eb-9458-7a1c53b5d58f.gif)

**Additional context**
* Raspberry Pi - Raspbian GNU/Linux Buster (10)
* Homebridge 1.2.3
* Node.js Version v12.16.2
* npm Version v6.14.4


