Under what circumstances am I entitled to cancel a contract?

A prerequisite for you to have the right to terminate the agreement due to a defect in the service is that “the purpose of the service is essentially frustrated and the operator realized or should have realized this.” That the purpose of the service is frustrated means, for example, that the defect is such that the service is practically unusable or that the result is so poor or deviates from what has been agreed that the service essentially has no value for you. The question of whether the purpose of the service is frustrated – essentially unusable for you – should be assessed from your point of view.

You may also have the right to terminate the agreement if the operator does not deliver the service within the agreed time, and the delay is not due to you. If no delivery time has been agreed, the operator is considered to be in delay if the service is not delivered within a reasonable time, taking into account particularly what is normal for a service of the same nature and scope. Reasonable time can therefore vary from case to case.