OP do keep all cards sent to you, log all calls made, any incidents you deem strange etc.
My HO harassed me for ages. I still am not sure why. But she ended up being removed from post when her behaviour escalated to calling me 8pm in evenings (ie outside Office hours) saying that there's been complaints from neighbour re the way I parked my car, noise (2 noise incidents she mentioned, Id been away on holiday so not even in the property, it was empty!) just all sorts of things.. sounding as if she was rambling . I had to stop answering the phone when I saw it was her calling.
I also had ansaphone messages from her whereby she'd called on a Saturday afternoon a few times, again outside office hours.
I complained and it was dealt with via their harassment policy. Senior management visited me, I gave them the log I'd made and also played back messages so they could hear for themselves when the calls were made. Then, she was gone. Strangely back then, I didn't report it early on as I thought it wouldn't be taken seriously as (a) it wasn't a man hassling me & (b) she was a member of staff.
Older and wiser Id deal with that sort of thing differently now. It was a horrible time as DCs were very little, and she made me worried and anxious about the roof over my head.
You're not a Housing Association tenant by any chance are you...
Don't let her get away with it OP. Good luck sorting it out.