Apparently this is not a tourist visa. Although business visas, like tourist ones, are coded with the letter "C". A visa with this encoding can not be renewed, but there are exceptions.

The inviting party should justify the necessity of your stay in practice - force majeure circumstances, provide proof of residence for the required period. All these documents will be considered and, possibly, the visa will be extended. But, most often, there should be a refusal in the extension justified by the fact that there are no obstacles to leave the country and apply to the Italian consulate for a new visa in the country of permanent residence.

On all visa issues you can apply to the Russian Consulate in Italy at: Roma, Via Nomentana, 116, tel .: +39 (06) 442-35-62 (weekdays from 8:00 to 12:00). From 19:00 to 08:00 you can contact by phone of the Embassy of the Russian Federation +39 (06) 494-16-80, 494-16-81, 494-16-49.