Best answer by Jon1
If you have followed he correct systems and closed your acct, then you have done all you can.
1. You cant sign your old landlord up as the acct holder. Only they can do that.
2. The letting agent is clueless for telling you that you can,
3. The landlord is now the deemed customer and they have to sign up to PP or switch to their preferred supplier again only they can do this.
If the estate agent says other wise then tell them to do one and go on a training course.