I need to clean my porcelain paving - these photos show what it's like.

Yeah - I know - I needed to clean it last year. In my defence this is the worst area - most of it isn't as bad as this.
I've used a stiff brush, and warm water with fairy liquid, and got these results:

As you can see, there's still some staining.
Are there any proprietary cleaners likely to be better, or are they just washing up liquid without the foaming agent?
I scrubbed reasonably hard - I could use more elbow grease if I had to, but would rather not as I've got about 35m² to do and I'm a lazy git.
Also, I've got a Karcher pressure washer - are their surface cleaning accessories any good?



Yeah - I know - I needed to clean it last year. In my defence this is the worst area - most of it isn't as bad as this.
I've used a stiff brush, and warm water with fairy liquid, and got these results:



As you can see, there's still some staining.
Are there any proprietary cleaners likely to be better, or are they just washing up liquid without the foaming agent?
I scrubbed reasonably hard - I could use more elbow grease if I had to, but would rather not as I've got about 35m² to do and I'm a lazy git.
Also, I've got a Karcher pressure washer - are their surface cleaning accessories any good?