Yes. Tbh it should in theory, be a two man job because the screens are sometimes heavy and difficult to get into place. But I normally work on my own. I know I havn't seen the site but personally I think £600 is excessive.
£250 or £600 may be fair - it may not.
We don't kmow the weight, quality, vehicle access, space to work in, how many floors up the bathroom is, perceived attitude of client.
We do know that if the decor or unit is damaged due to one man struggling, the client will be looking for compo. inwhich case there won't ne much wage left from £250 after time, materials, overheads and compensation.
I would have thought that Starman would have got another quote.