Fresh Plaster Cracking Within 24hrs...

Hi,

We had our bathroom walls and ceiling plastered yesterday.
Two walls and the ceiling are new plasterboard, and two solid block walls were plastered over the remnants of a sand/cement render left from removing old tiles and plaster.
The two sand/cement rendered walls have started cracking and blowing in places already. Other threads on here suggest that the plaster has dried too quickly, possibly due to poor preparation and sealing of the very porous render base.
The plasterer is returning on Saturday to rectify the problem. I have lost a bit of confidence in him and the job due to this, but prepared to let him have another go (we've not paid yet.)
How will he do this, will the plaster on the two cracked walls need to come off?
I'm asking because I don't want a bodged repair doing that'll crack and blow again after we've paid him.

why not post pics of inside the b/room and the outside wall(s)?

Here you go. There are patches like this on pretty much most of the two sand/cement rendered walls...

thats a bodge - the guy's not a plasterer who did that. there's no prep and or a bad mix.
It needs hacking off back to raw brickwork, and starting again from there.
closely examine the taped join lines of the plasterboard skimmings - odds are that they are duff too.

you dont show or say about the outside surface?

The plasterer is a local chap and came well recommended from others who have used him. He's been full time plastering for over 30 years (my bro-in-law went to school with him and can confirm!)

The plasterboard work is faultless; smooth with good sharp internal/external corners and I can see bits of exposed tape near the floor as 'evidence' that he has done the joints properly. The ceiling is the same, very well done.

The picture is the inside skin of what used to be an outside wall but is now inside due to an extension. The plasterer has said himself, "It's dried too quickly" when I texted him a photo but he also said, "No dramas". which is why I sort of suspect a possible bodge repair rather than a full hack off and restart if that's what you reckon needs doing?.

I'll be at work when he comes round, so unable to keep an eye. However, if I can tell my Mrs what needs doing she can make sure we don't get seen off!