What is the ruling on taking 100 Russian rubles as compensation for an additional cost (50 rubles) and a reduction in the duration of stay (50 rubles) due to the company's failure to adhere to the original agreement?

There is no issue with the entitlement to reclaim the amount paid to the company after the contract is terminated. As for any additional amounts beyond that, there is no right to claim them unless significant damage occurred due to the termination of the contract, in which case there is a right to claim compensation for that damage.