Blunder

On twitter dstv posts a competition, its about amameme i decide to enter, luckily last week on the 14th of April i get a call from this number ***, nd they say u won a 3 month payment break on us, kindly confirm ur smart card number and decoder serial number, i do that the call is exciting at that time and he further adds don't pay we will pay for u mind u my due date is on the 15th of each month, i got really happy man dstv is giving back that's really dope I'm grateful, then on the 20th of april i get an sms in the morning stating services disconnected due to non payment? Pay R600 to re connect? Sm mafa, 1747 mokwena street moletsane soweto, ***, ***. Can someone please advice and assist?