At least the day before the show please contact the box office of the circus. You have got to have a ticket and passport. It is also desirable to have a check at the time of purchase. Tell the cashier that you want to cancel the ticket and get the money back. You have to return it full price. If you do not want to return the money or offer to pay only part of them, write a letter to the management indicating their requirements or ask the cashier that you made to the administrator. Pass the statement to one of the responsible employees of the circus, and then ask them to give you a copy with the stamp of the organization.
If your statement had no effect, send a request by registered mail. At the same time you can contact the division for consumer protection, and even write a complaint to the authority municipal of the state government dealing with culture. You also have the right to sue on the administration of the circus. But keep in mind that the proceedings in such case it may be long and costly, so such treatment does not make sense, if we are talking about one or two tickets.
As a compromise, you can offer the tickets to another date or another view. To them easier than to return the money, so you can make the decision on this matter.
When you replace or cancel the submission of the ask for a refund, even if the time of submission. You have a right under Russian law.