Alarm bells should start to ring when they say they are going to claim on their insurance surely?
Oil stains will not come out of block pavers using a pressure washer no matter how hard you try.
Even if using the best oil stain remover available there is no guarantee of a satisfactory result.
As mentioned sometimes the best solution is to replace the stained blocks.
I also think unless you can get the whole area clean and remove all hard to remove black spots, algae, lichen, oil stains etc which can be a challenge itself on some it's rather pointless to seal the blocks as will look crap afterwards.
Best to also find out if the blocks have ever been sealed before and with what sealer or you could get a reaction with different types of sealers used.
Classic 2 mistakes when sealing is when sand has been left and/or gets onto the face of the blocks and joints being overfilled which also results into a crap looking job.
Apart from that cleaning, resanding and sealing block pavers is a doddle. That is apart from the 3 seprate visits you have to make to do all 3 properly.... weather permitting.
So that 250 and all the costs involved and hassle you might encounter don't sound very appealing now does it?
