The flat and location were great, but on our first night it became clear the heating was broken and it took until our fourth day for an alternative (a portable space heater) to be provided.
Each individual working for City Relay was polite and happy to help, but their internal communication was very poor and we frequently had to re-explain issues and remind them of promises made. A good example is that it has been two weeks since our stay and we’ve received no compensation to date for the missing heating (in sub-zero temperatures), despite repeated promises to the contrary.
The flat is very nice otherwise, but if you have an issue, I would escalate to AirBnB immediately.