Additional information: “It depends on the context of a contract, but it means a breach that goes to the heart of a contract, the whole purpose of the agreement,” says Mukhraiya. And if you mention the Consumer Law and the Unfair Contracts Act, you will see that the company is much more willing to be reasonable. “Their use of services and content must be consistent with the rules set out in this contract. Any other use of services and content constitutes a substantial violation of this agreement. Contractual guarantees are less important conditions and are not fundamental to the agreement. They cannot terminate a contract if the guarantees are not fulfilled, but they can claim damages for the losses incurred.