So long story but, we bought house in September 2015. Knocked down a sun room and replaced with a 3x 5 metre extension. Architects were employed who claimed they had done it to permitted development rules. Now we come to sell buyers solicitor disagrees and wants retrospective planning permission. If we do this then we lose house we want to buy due to planning permission timescales.
It's all building regulations passed and we have a completion certificate. What do we do?