Blackview SA are abusing their clients trust

The most unhelpful service provider I ever encountered. Took my BV8800 in for repairs (replacement of the charger port). The phone was working 100% except for the charger port that was faulty. First of all they INSISTED on an upfront payment once the fault was "determined". This payment was for the replacement of a faulty charging port with a NEW unit. When I went to fetch the phone after the "repair" I found that the rubber cover over the port was pinched when they closed the phone body, thus rendering the rubber piece ineffective. No test was done in front of me before I took possession of the phone to ensure that the "new" port was working. Upon getting home and wanting to charge the phone, lo and behold, the "new" charging port still did not work. I could also not connect to my vehicle Android Auto feature. I had to take the phone back and after waiting another 30 minutes for them to have a look at the problem the lady informed me that even she was not happy with the replacement and she is going to order a NEW charging port to replace the one they installed. The question begs, did they then make me pay for a used/faulty unit which they probably salvaged from another faulty unit. This after they stuck a QC sticker on the phone when I collected. This company is a farce and I feel they need to be seriously investigated for *****ulent service provision. It is now nearly 3 weeks later and even after following up they are ignoring me and it seems they are not going to assist me further. I need them to refund me the R900 that I paid for the non-repair that they did and I will have the phone repaired by a reliable service provider.