RCS / Game Stores Pathetic Booking Keeping

At the end of 2011 I walked into Games Stores, Centurion Mall with a smile on my face, as I was walking in in order to pay my RCS account in full and close my account...thus getting rid of debt. I made the payment in cash to the store after which I rejoiced and with a smile on my face asked the lady behind the counter for a scissors as I wanted to cut the card up. I still feel bad today because in the process of cutting the card, the orange scissor's handle broken and I still offered to but the lady a new one, which she declined. In 2015 (4 years later) I received a E-mail from RCS's debt collectors stating that I owe them +/- R 1,300.00 upon which I responded asking for more information stating that my account had been settled and closed four years earlier, upon which nobody responded. I contacted Lesego Modisane from the debt collectors and inquired about this account to which she promised to contact me once investigated...which never happened. Now in 2018 (Another 3 years down the line...7 years in total) My wife is suddenly contacted by the debt collectors threatening her with legal action if we do not pay immediately. I lost my cool and contacted the debt collectors and cut the call 40 minutes into waiting for someone to answer...I contacted RCS who does not quite understand the fact that the account was paid in full and closed in 2011....and still demands payment!!! Why did RCS not attempt to make contact with myself over the past 7 years? What happened to the payment made at Game Centurion?