new boots

Purchased a pair of knee high boots .had a voucher for 20% off if you spend over £20
boots were just what I wanted staff at the check out very friendly. As I left the store in cardiff I bleeper went off
I felt a little embarrassed by this .I was asked to show my recept which I did I also asked how this security man happened. The security man said this often happens . A lady member of staff who came to my rescue took my boots and had then put through security again ..as she waved the boots through the door way the buzzer went off for the second time . The lady appologised . By this time I had had enough and asked to speak with the manager on duty .
However I was offered a further 10% off for the inconvenience I had been through which I accepted as I realy liked my new boots. I will shop there again the two ladies who handled the situation were very good and appreciated the inconvenience I had been put throw thank you both (cardiff materlan) ps the security man informed me if I wore the boots this will stop the buzzer going off the other shops . Dont know what planet hes on