Cannot update simple contact information

I personally do not have an Old Mutual account, however one of their clients have given them MY email address instead of her own , I do not even know this person, I am constantly receiving this person's personal money account notifications, and other spam emails addressed to her since March of this year, which is reckless of them, I thought you are supposed to protect your clients personal information? Your lack of professionalism and attention to detail is really quite shocking. I have called them and notified them of the mistake and they assured me it was corrected, but not surprisingly it was actually not amended, I have since sent close to 10 emails to advise them or their error. I have even sent their client an sms to tell her to rectify her details with them, and STILL TO DATE I am receiving emails intended for someone else! What more should I do to fix YOUR mistake, its really starting to infuriate me now. Please would someone get in touch with me, to get the relevant details, and correct this. Thanks