21. A recall notice may only be issued by the enforcing authority where—U.K.
(a)other action which it may require under these Regulations would not suffice to address the non-compliance;
(b)the action being undertaken by the relevant economic operator is unsatisfactory or insufficient to address the non-compliance;
(c)the enforcing authority has given not less than 10 days' notice to the relevant economic operator of its intention to serve such a notice; and
(d)the enforcing authority has taken account of any advice obtained under paragraph 22.