Threats received from Seeff agent

After a traumatic experince renting out a property through Seeff and a comment relating the events on Hellopeter, I received (13 months later) the following threat from one of their agent:

The landlord had the keys to the property after you moved out and I have a trail of emails where you and I discussed the key matter. It was a managed property through Seeff which means that our maintenance division handled all maintenance issues, and not me. At that stage it was ***x ***x and ***x ***x.

The owner took the keys at the outgoing inspection and after that it was handed to the Seeff Maintenance division when you said you needed it. I was never in possession of the keys again after your last inspection.

It is now long gone being a year later but I would like to request that you remove your post from the Hello Peter site please for it is slandering the Seeff name and me as a person and as a professional. Posts like your's can be very devastating to our company. I have a right to recourse of defamation and false allegations and so does Seeff but we would prefer to not go that route.

I have never had a customer complaint of this sort and I've been in this business for almost 7 years. The landlord of ******x will vouch for me as well as the tenant before you.

Please can we resolve this in a kind and peaceful manner so I can inform my Seeff Principal of how we should proceed.