Do you have access to pine needles or bracken? They both decompose to produce an acid compost. Not a quick solution I'm afraid.

Or mix in a bag of ericacaeous compost?

If your bed has a high ph it will often be controlled by the type of sub-soil as particles (i.e. chalk) rise to the surface. The upper part of the bed can be changed, as suggested, but this will be a constant chore. Far better to grow plants that will thrive in a high ph soil.

Thank you to every one for their help with this. I do appreciate it Bob