Unprofessional service from admin clerk and director and not treating clients fairly

I was revamping my kitchen and ordered material for Niemann, Materials where delivered to me and 4 large boards where returned due to incorrect sizes. When I requested for the 4 Boards I was told they know nothing about these boards and this costed me a large sum of money, I had been battling with niemann for a long time to no avail. I Then contacted Kitchen Specialists(KSA) to help me out. I completed a dispute form and waited to see the outcome. As a client i was banned from entering the niemann premises for reasons I was not aware of. The director of niemann refused blatantly to meet with me to discuss the issue. A meeting was held between KSA and niemann and they made a decision without me being available, so I have lost money here. KSA and niemann sa refused to include me in their meeting to discus this issue. Secondly I gave measurement to niemann admin clerk to cut boards for me and that again was stuffed up by her and niemann refuses to sort the problem out. Is there any other route I can take this up to. The incompetency from the staff is unreal and the director does not value his clients, its is more making money than customer service