I contacted them from the e-mail address in the description of a YouTube video. I have mobility issues, and I requested a private guide who could split the four hours walk in StoneTown into two two hours tours, one in the morning and one in the afternoon. Yussuf, the guide assigned to me, arrived at my hotel on time and could not have been more patient and attentive. I sat several times during our walks, and the couple of times I had problems (high steps or slopes), he helped me with a smile and spontaneous courtesy. The experience could not have been better.
Yussuf was also very informed, and in the four hours (in total) we spent together, the conversation was never forced or stilted.
Booking and payment via WhatsApp and a link could not have been smoother.