Our neighbour has attached her rainwater guttering to our drain down pipes without our permission and knowledge

Our neighbour has attached her rainwater guttering to our drain down pipes without our permission and knowledge. We were only made aware of this by a chartered surveyor who said this was a Trespass. As we are trying to sell the house we removed the pipes and returned these to her by placing them in her garden. Unfortunately the situation with this neighbour means we cannot communicate with her as she is so abusive and aggresive and has been harrassing us for over 18 months. She has now contacted the police and we are being asked to attend an interview under caution for criminal damage. Surely it is criminal damage to make alterations to our property without our permission and we have a right to return our property to the original state? Any advice please.