mutual exchange

Hi I posted in the past about the 42 day mutual exchange rule. Well its been about 82 days but the exchange has been accepted only now a week before sign up we have been told to reinstall the night storage heaters (we took them out) and get a minor works certificate. I didn't think they could refuse after 42 days had passed. Thanks as always for any advice as this is causing major stress us its a 5 way swap and we are all packed up.