David turned up for job at the time he said he would, and proceeded with the job immediately. Unfortunately, he was unable to clear the problem, but this was because the issue wasn't actually in my Flat, but in the communal waste pipe. But he did advise me what to do and was going to send me a report on the issue, so I could present that to the Freeholder.
Because he was unable to sort out the problem, he didn't charge me.
Because of this,I will definitely consider David for any future works I have planned.