I'm not saying Essex Camera Service can do everything, but you get a 30 day guarantee. If you ask for an "A" and they charge you for an "A", the camera has been "A'd". Otherwise you send it back or ask for a refund.
Essex doesn't accept jobs they know they can't handle. Estimates are free.
Best to ask him directly. But based on my recent CLAs, he provides a 90 day guarantee.