Finger in the air time.

My brother has just had a shower replaced. It was a bog standard Mira mixer
shower, hot water feed nearby, no new plumbing involved. The plumber said
that the plasterboard behind was rotten, so this needed to be replaced as
well. Basically, we're talking about a new ceramic tray, new tiling (big,
cheap, easy to cut tiles) new shower and new enclosure. Think Ford Mondeo
and not Bugatti Veyron.

How much should this cost, as a very rough ballpark estimate? The bill for
the work has come in at £1600 which seems a tad on the steep side to me.

Thanks

Edward