*****ulent SIM charge

I bought a phone over the phone trusting a *****ulent Company Blue label Connect then the phone with a sim arrived only to find out I dnt like it ,called them and agreed to collect with a cancellation fee R479.00 which I had no problem paying them .The phone together with a sim was collected in then surprisingly after 4 months they calling saying the SIM was not allocated ,then I have to pay R479*2 for SIM I sent together with the phone and they threatening to affect my credit score.Question is did they investigate their courier and why don't they track the SIM card,or they just used to *****ing clients.