No accountability for poor installation product

They installed a heat pump for me, I used them for the installation as I wanted to uphold the warranty as I purchased the unit from them. The unit was installed and 2 weeks after installation I found that there was a leak on a T Piece, I requested for them to come out and fix it, they came out after a few days but the issue was that when they arrived that suggested that the pipe was damaged by someone

There was no physical damage of anything, Then the story changed that it was maybe due to us using the system incorrectly, we have not started using the heat pump. Then the story was that maybe something fell onto that pipe which is not possible as there are pipes above this pipe and no ways of something falling and not damaging the pipes directly above this particular T Piece, the pipe was leaking at the seam of the pipe, which is a common place for a leak as this is the weakest part of the pipe

They insisted that I pay R1500 for them to install a new T piece pipe, after deliberation they said that could reduce that fee to R1000. I was not going to pay R1000 for an inferior part that was fitted so I spoke to the manager but he was not willing to do anything despite him not being able to find any damage on our behalf

I emailed them again after to request for them to fix the fault but no response

Their after sales service and accountability is dreadful