IMHO the OP is asking tradesmen to be lawyers, with only minimal evidence on which to base a case. This is not fair on him, his plumber or you. By all means, the specialist tradesmen here can comment on the quality of the work done so far (that we can see) and what corrective action is required. The OP cannot reasonably ask us what to do with £500. Thats between him and his plumber. All I can say is that £500 is approx 40% of the labour charge and does the OP have the right to withhold that proportion of the charge? Fair comment has been made on the workmanship and thats as far as this discussion can reasonably go...IMHO
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