The review below is the personal opinion of Florian and not that of SafariBookings.
Not a trustworthy provider, better pick one of the many others.
I booked a one-day trip to Ngorongoro Crater with Erastus and we agreed that we would meet the day before to make the payment. We met and Erastus told me that he might not be able to arrange the trip for me because other guests had changed their plans. However, he personally, sitting in front of me, promised to make it work and told me not to worry about it.
The same day, at 8 pm, he informed me that I could not do the safari the next day (NB: I had only come to Arusha for one day to do exactly this safari). Despite me calling a bunch of other operators, it was too late to find an alternative for the next day. I ended up not being able to do the safari that I had come for.
Don't trust Erastus. My whole trip to Arusha was useless because he promised things he couldn't keep.