While we try to be as thorough as possible with all estimates, we do not guarantee that our estimate is all-inclusive and final. Often, it is very difficult or impossible to identify every problem affecting a device until some work is performed. Our estimates may evolve or change during the course of servicing the customer's device. Our initial estimate will always remain valid within the scope of the services it was originally attached to, though we may advise the customer that the original service may have become unnecessary or unlikely to resolve the issue.
https://www.bytenerd.co.uk/terms/