FNB wants to serve me with legal notice for a credit card I never app**** for.

3 years ago, FNB granted a discovery credit card to an imposter who used my details to apply for the credit card. 2 months later, I noticed the credit card on my record and I contacted them to have it canceled and removed from my name. Despite sending them all the requested documentation and constantly calling to follow-up, I never got feedback from them, and a while later, I was contacted by debt collectors, who informed me that they were requested by FNB to collect the money for the same credit card. After I told them that I had disputed that card, they asked me to get new documents, and also forward them the previous documentation as well as the communication with FNB, which they would escalate to FNB. Once again, I got no feedback once the documents were sent. Yesterday afternoon I received an SMS from Groenewald Lubbe Attorneys that said they would be serving me with legal notice. When I called them, they said FNB had requested them to serve me with the notice for the very same credit card I've been disputing for the past 3 years. Who do I talk to at FNB regarding this matter?