Non compliance with permissions - increasing?? - Public forum - Planning Advisory Service (PAS)

My authority has experienced over the last 6 months increasing number of cases where applicants have not complied with conditions (especially tree protection) and/or have not stuck to approved plans and carried out all sort of changes to approved schemes without recourse back to LPA. Not only is this causing extra work to sort out but raises concerns from residents and members. Have others experienced this as a trend? And if so have you taken measures to deal with/education etc.? Thanks