The state customer was not warned about the additional work — the courts did not collect their payment
The parties agreed to build a bridge. During the execution of the contract, the contractor revealed that the actual amount of work did not correspond to the estimated: the bridge turned out to be more than 2 times longer. Later, the customer was asked to pay for additional work, but he refused.
Three instances did not collect the money:
additional work was not coordinated. The customer did not sign the local estimates, the parties did not formalize the agreement;
the contractor did not declare that the contract could not be fulfilled, and did not stop construction;
the customer was not informed about the need for additional work. The contractor applied for their payment after acceptance;
the urgency of the controversial work has not been proven. Prior to the conclusion of the contract, the contractor knew about the conditions of its execution.
The arguments on the approval of additional work in correspondence were rejected by the courts, because they did not see a consistent, explicit and affirmative consent of the customer to increase the contract price.
Note that in practice there is an example when the customer was charged for additional work. The courts decided that they had been agreed upon by conclusive actions and correspondence, and the absence of a written warning did not exempt the customer from payment.