Vauxhall new astra 04 screen wash?

Hi screen wash stopped working on the first day of the big freeze, the well at the base of the wiper blades was full of ice, which I have cleared, at the time I thought it must be frozen, I checked the bottle was topped up. The weather is much warmer now 5 to 6 degrees , and its still not working.
What's the most logical way to look for the fault?
Thank you all in advance.