I wish we could Ali, unfortunately DP's ex wouldn't tell him where the counsellor is located or anything - and now she just doesn't answer her mobile or return calls / messages when DP does call (to say Happy Birthday to his eldest DD last Tuesday...). Sad situation.
in this situation, i'd be trying to arrange mediation through family relationships or something similar - if she doesn't show. you can get a certificate to go to court and fight for access via a court order - if she doesn't comply, she's in contempt of court. if there is REALLY evidence from counsellors, she'll have to provide it at mediation or court to get the orders for her kwim? it's not ideal, but it will at least give you this so-called evidence... i think having you care for you step daughters while their dad works is completely different to Tan's DD being looked after over night by Nan while her dad goes off to visit his GF - if he's a shift worker, and you could work out access weekends to coincide with night shift, at least he'd still have periods during the day that he can spend with them - he's not abandoning them, he's working to provide for them (cos i'm pretty sure he'd still be paying child support even though he doesn't see his kids!!) - very different to running off ALL night for a shag!