SABC TV Licence Harassment

Last year I turned 70, so I decide to take over the TV licence from my wife, as I was under the impression that I would get a discounted rate. I filled in my details, but discovered that the benefit only kicks in at 71, so, because my wife's licence was still valid, I paid another year on her name. I have subsequently been getting letters of demand from lawyers for outstanding licence fees. I sent the proof of my wife's licence and enquired why a single household needs two licences. My wife still get weekly SMS demands to pay the outstanding licence fee. How can I stop this harassment.