Below is my availability calendar. Find the day you were planning to do the tour there and make sure that it's free. Then use the form on this page to reserve that day for yourself. Voila! Bob is your uncle!
If the day says "Booked 5-8 PM" for example, it means that I believe there's a possibility to fit more tours into it before or after the booked time slot. If it says "Booked All Day", then well... it's booked for the whole day. Try to reserve another one.
If I'm not responding to you for more than a day after your reservation, you most likely mistyped your contacts during booking. I won't be able to reach you in this case. Try to book again or use my phone (+7 (985) 447-86-88) to reach me directly through WhatsApp.