The initial implementation of the project was calculated for one cost. Then, after discussions with the customer, it was clear that certain moments of implementation will be a bit more complicated, due to which the cost of implementation of the project increased. The contractor agreed on the new conditions, and the process of implementation of the project began.
The project, as planned, was completed over a few days. However, the closing dates of the project were transferred by the contractor, and later extended for a few weeks (project corrections were not carried out).
In all the other aspects of cooperation, all was harassed, problems did not arise. In general, I can recommend cooperation.