Sterns marketing without consent

I visited Bethlehem Sterns the end of May and purchased a diamond necklace from their shop. The cashier wanted all my details, phone, email, id number, blood group etc. I eventually paid for the necklace (cash) and was on my way. NOW - here is where the **** starts. I never agreed to marketing emails or phone calls, but every day I get an email about Sterns specials and phone call on behalf of Sterns from TFG. I will never ever buy anything from them again. You can unsubscribe from their emails as much as you want, tomorrow you will just get another one.