Hi There thanks for the reply!
It is a raised bed to which I added soil from a landscaping company which claimed to be "PH balanced premium garden soil" Tosh.
I've used triple mix in the past for new beds and have never had this issue, so I'm annoyed by the poor quality soil I paid good money for.
I didn't add anything to it and didn't till it at all. It rested all of a week before I started planting, which I'm sure wasn't ideal.
This is a new house, so I haven't got my compost pile up and cracking yet. Would garden centre compost be ok?
I can get rock dust, but I've never heard of green sand, will have to investigate that. For those two, could I add them to the top of the bed and let seepage do the work for me or would I till that in?
Again, thank you for taking the time to help!