Poor service when decoder has technical issues

My decoder started with issues. I took it to the Multichoice walk in centre in Randburg they swooped the decoder for a new one. Brought this one home gave error hard drive ******* and would not work. Took it again to the walk in centre in Randburg and they swopped it for a 2nd unit. Brought that one home. Hooked it up and it won’t boot up. Call the help centre and they told me I have to take this one back again for a 3rd one. I am not prepared to do this as to what guarantee do I have that the next one will work. Very poor service.