Sale subject to agreement to sign section 27?

Hi experts,

From vendor’s point of view, can a sale be made conditional upon buyer’s agreeing to sign
section 27 for deposit release?

If so, can it be further condition to have deposit release within certain days/weeks?

I am selling a property and I raise the question to my solicitor and the response I get back
is “buyer is not obliged to sign section 27”.

And then he went on elaborating section 27 is supplied by my lender and the hold up may be
combination of how soon lender produces s27 to buyer and how much time buyer takes to respond.

Is there really no way to legally enforce deposit release as condition of sale before settlement?

Thanks,
FXD