No Smart cards for decoders.

Last Wednesday we went to exchange our decoder since it was broken. We went to Aerial & Satellite Excellence in Water glen shopping center. They could not pair the 2 decoders and said the smart card on the one is faulty. They did not have any smart cards. Today my husband phone still not smart cards. How can this happen. We pay a lot of money to watch DSTV and for assurance. We are pensioners and this is just bad treatment. I now see why so many cancel there DSTV. Can i please get a explanation what is going one with the smart cards.