supply of goods not as described - advice please

[mypinkmonkey]

We have started a garden project - terracing a very steep garden using gabions for retention. We bought stone (£4K in total) to place in the front of the gabions (not as backfill) from a local stone merchant (recommended by the landscaper). They knew what we were using it for and showed us a board with samples of the stone we would get - we based our decision to buy on that representation.
The stone has been very poor and not of a good enough quality to use in the gabions. We complained and they supplied us with more at a cheaper price but it is no better. We estimate that only one quarter of each ton has been of the correct quality.
They have basically ignored all of my calls, emails etc. I have visited the quarry but they fob me off - the guy we dealt with originally is never there or hiding! And the rest of them are quite scary.
So I am drafting a letter to send them stating that they are in breach of the Consumer Rights Act - goods not as described, not fit for purpose etc. My problem is what do I ask for? We can't return the stone - we had to move the bags down the garden and the poor quality was only revealed when we split them. I have calculated that it is going to cost me at least £1k to buy enough stone to finish the project. My guess is that they will ignore me anyway and we may end up in the small claims court - what are my chances of success? TIA

So the stones provided have been used but as backfill instead.

I suggest that you ask them to provide further stones (for the decorative part) free of charge (if you would not have needed more stones in any event) or ask them to come and remove the stones at their cost and replace with correct stones. Or give a refund for an acceptable amount to allow you to purchase some elsewhere. I assume if you keep the existing then you can get away with less now?

Set them out as different options labelling them Option A, Option B etc.

If you do need to go to small claims then make sure you have pictures of what you expected and what you got.

Price up what it would have cost and what it will now cost and the claim will be the difference between the two (plus expenses phone call,s trips to see them (petrol) etc.

Thanks very much for your advice HereIAm20
I am very cross that we bought more - I had told my DH that the quality wouldn't improve but he wouldn't listen! My view is that they are running a scam - fill bags with rubbish stone, place good quality on top so all looks ok on first inspection. Anyway lets hope my letter produces a good result.