Pathetic service I received

I bought the cellphone from Ackermans store in Ficksburg 24/01/2018 and during March 2019, was not working and I took it back to them, it came back and after few days I had to take it back as it was worse, I had to take it back to them and I received sms saying I have to pay R1700.0 for liquidation which I don't understand why they did not see it at the first time, I declined the sms, today I called the shop asked about it the consultant said I have to pay R300.00 for the courier which I was not informed of, the only cash that I was informed is that if I had to pay I will receive sms and if I respond with yes iy will be fixed, if not it won't be, I responded withno but the wait for me to call and tell me I have to pay courier that I know nothing, I still feel that It is a pathetic service that I received as they even gave me MTN no to call instead of them doing that on my behalf because i bought cellphone from them not from MTN