I used to book hotels in Odessa with booking.com and had few problems with their bookings:
Once they gave me price that was higher than a hotel price. The other time I have cancelled the room well in-advance (before the due date), however the hotel still charged me the 1st night for "no-show". And Booking.com is no help when a problem arises with a hotel.
There are many reasons why I now use odessahotels.org.ua. I have stayed on two trips with them and no problem. Although I have to give my credit card details to them they never charged me anything.

  Somtetimes, it takes time to receive a confirmation email.

  I've used this service several times and have never had a problem. This platform is very convenient. odessahotels.org.ua is one of those agencies that do not take any money off you at the booking, you pay the hotel direct. I received exactly the rate I was promised with no surprises. Once I arrived quite late at the hotel, and my room was held, as promised.
Another great thing about this site is that they display guest reviews on their website. These can be really helpful when deciding which hotel to book.

  The only small downside is that their site doesn\'t have any information about their office working hours.The manager sent me an email asking me to reconfirm my reservation and stating that their office is closed on weekends (it was a surprise for me). I wasn\'t worried since in the same letter manager left me her personal phone number in case of any emergensy situations.

  Booking process was very easy. You just select the room you want and then fill in your details. Then manager asks you via e-mail to register your credit card information with them to guarantee your room. The credit card is just to protect them if you don't show up without cancelling. Then you get Email Confirmation and you print your Confirmation off to present to hotel.
So if you are the sort who does not like paying in advance then this is one for you.
Also this site often appears to have lots of special offers as well, especially in the winter season, so take a look and you may find something to suite you.