Blue black granite staining - New patio covered in black marks

[Alex10001]

Hi
We had out blue black granite laid a few weeks ago, it looked fantastic (pre-grouting/pointing) and dried perfectly even after all the rain we've had. 5 days ago, they added the grouting/pointing (Stonemarket Fast Point) and it's looked horrible ever since (photos on link below). Initially it looked like a lot of dark stains which I assumed were stains from the grout. They then used something to wash the stone and the stains are still there but admittedly they are a bit lighter. However, 3 days ago, dark stains started to appear around the edges of all the stones and haven't yet gone. The guy who did it is mortified and has offered to buy new stone and relay it, but I really don't want to go down that path as it's a complete waste of materials and to be honest, I suspect the same thing will happen. So my questions are:

1) What could be causing the marks around the edges? It's been suggested it could be either stains from the resin or because he may have used a non-permeable grouting instead of a permeable one (not sure if Stonemarket Fast Point is permeable). Do either of these seem like feasible reasons and if so, can it be fixed? (How??)

2) For the other marks, what would you recommend to attempt to remove them? I've read that acid cleaners should not be used on granite but want to check if this is correct.

3) Is there a go-to for a list of experts I could ask to come out, take a look and do the remedial work if possible (we live in St Albans)? I don't want anyone to try to sell me new slabs if what we have can be fixed!

3) If all is lost and this can't be fixed, we will need to look at getting new paving slabs. I really like blue black granite but is it known for being stained easily and should we be looking at a different type of we don't want this? I'd be happy to put the work in to maintain it if there is a way to do this.

https://www.dropbox.com/sh....oa?dl=0

Thanks for your help.
Alex

[Tony McC]

Picture framing caused by use of a permeable jointing compound over an impermeable bedding layer - see previous thread