I'm pretty sure there is no Apple nor Apple authorized support for iPhones in the Ukraine since there are no Apple Authorized resellers for iPhone in the Ukraine and no carrier in the Ukraine officially supports the iPhone either.
Sorry, guess I'm wrong on the carriers since recently KYivstar and MTS are listed as officially carriers - Wireless carrier support and features for iPhone in Europe - Apple Support so I would try asking them. If those two carriers sell iPhones, then they are also the service providers for them as well (as indicated in that apple link). They may not provide service though if you did not buy your iPhone from them.