Watten Construction contracted to build the Sillimans a house for $50,000. When Watten began digging the foundation, it hit bedrock, which was highly unusual in that area. Watten told the Sillimans that he required an extra $5000 to build the house. The Sillimans agreed, but when the house was done, refused to pay Watten any more than the original contract price. If Watten sues the Sillimans for the extra $5000, what is the result? Why?