I would simply ignore.
Any information you give them now is likely to be to their advantage, especially if you remind them of their failings before it's too late.
The implication being that they are more likely to discontinue before paying the court fee on 30 July, so they're scrambling to get "something" at the eleventh hour.
However if they do pay the fee, you've then got a week to compose a witness statement as you know. I just think this means it's less likely that they'll pay.