Nonstop Harassment to renew Deceased Father's magazine subscriptions from HSM

I had a gift subscription for my father for car and getaway magazine from HSM, my Father passed away a year ago and these subscriptions have since expired.

I am continuously being harassed by about three different sales people via email up to two times a day to renew these subscriptions, even after telling them that I am not going to renew it.

They even go as far to send emails to Gerhard (my late father) telling him to express interest in his expired subscriptions which I find really disrespectful.

I have sent a complaint to info@hsm.co.za and a sales coordinator apologized and said he would sort it out, only to receive TWO emails from a sales person two days later.

How do I stop this painful harassment??

JJ