Harassment in store by staff

So on the 13th Saturday morning I walk into builders warehouse at just past 11am to buy a few things. Not even a second inside I get approached by some guy asking do I know the advantages of a builders warehouse card, I kindly declined, then went on to get the stuff to purchase, we decided to have a brunch and then pay for the items, on our way to the tills there was another guy who approached me again asking do I know the benifits of your card, I said no thanks then he has the nerve to try and get my grandmother to sign up after I said no, who do you think you are trying to force a person to sign up for you ****ty loyalty card ****? What gives you the right to send people out in the store to harass paying clients? **** you I will never shop at any of your stores again, to top it all off there was no manager in sight and your staff at the tills just give you a blank stare when asking for the manager. **** right off with your company.