Hi Linkin and welcome.
Have I got this right? You were late submitting your police certificate so INZ decided they would not renew your WP? That sounds a bit harsh, but I do know they have rules and often tend to stick to them.
Could your employer contact INZ on your behalf and state that they still need your services? I'm not sure how much weight this action would carry but it may be worth a try.
Alternatively perhaps you could appeal to the
Removal Review Authority under Sec. 47, but you have to do this within a certain time.