Cash Crusaders Vaal Mall ripped me off

In December of 2017 I bought a Hisense smartphone for R600.00 for my husband from Makro. After I set it up for him he decided he didn't like it. Makro refused to take it back so I went to Cash Crusaders at Vaal Mall to see if I could get at least something for it. They switched it on and checked the phone and offered me R350.00 for it which I accepted. Yesterday someone by the name of Talita phoned me from Cash Crusaders Vaal Mall and said they needed the email address and password to be able to format the phone and would I mind coming in to the store to help them with that. I was puzzled by that as I was under the impression that I had formatted the phone before I took it there. Anyway, in the spirit of co-operation I went in there this morning. A man by the name of Lucky brought the phone out and switched it on so I could sort out the problem with the email address and password. When he switched the phone on a series of dots appeared and I was asked to enter a "pattern" to activate the phone. I had no idea what this "pattern" was supposed to be and don't recall ever seeing something like that before. (Bearing in mind this is now 6 months later) As they were then unable to unlock the phone and sort the email and password problem out, I was told that I would have to give the R350.00 back to Cash Crusaders. Now you tell me, if they couldn't even unlock the phone how did they know that there was an issue with the email address and password? It's been 6 months since I sold the phone to Cash Crusaders and I have no idea who was doing what to it in that time. The phoned was tested and approved when I sold it to them, now suddenly the issue with the phone is my problem! As I had already wasted so much time there, in desperation I went to the ATM and drew R350.00 and gave it to them and in return I was given the phone back. I feel that I was completely ********** by Cash Crusaders Vaal Mall after trying my best to co-operate with them. I will not be doing business with them again.