Very Disappointed

I received a call from Mr Price not exactly sure of the date but it was in June 2019.The person i was speaking to told me that Mr Price wants to thank me for being a loyal customer(by having an account with them)so they are rewarding me with a sim card which includes data,airtime and sms's.I didn't think there was in any harm receiving a sim card so it was delivered to my work address.I didn't open or use the sim card.On the 08 June i payed up my account and knew i don't owe anything.On Thursday 11 July 2019 i went to Mr Price Wonderpark to purchase and i asked the teller there to check and make sure i dont owe anything only to find out i owe about R700 which was very alarming.She went on and checked the transaction statement which showed i purchased airtime,data which i didnt and it had a date of 08 July 2019 when i purchased.They were so helpfull that they contacted i think its head office and i spoke to Kumheshan at 11:45 on the 11 July 2019 whom i explained the story where the guy said the sim card its for free i further told him why would i take a sim card that is on contract where i have a cell phone that is on contract:He said they will have to listen to the recording and come back to me which takes 48 hours to be done,I gave him my cell number ***,told him my name Lerato Chiloane.I have been waiting for them to come back to me and they haven***** been over 48 hours and nothing is happening. Please Hello Peter assist