Bad customer service and disrespectful attitude from the company owner

I bought a car part from them that needed to be coded to work with my car and key and on the day of collection I had to wait for more 3 hours and when the part arrived I asked about it being ready to be used and the consultant lady called and asked her boss and the confirmed it’s ready when you get home you just plug and play your system would be ready to read it. I got home and did as I was told but as soon as I plugged it in there was a sign of the car not reading that unit so I called the onwer of the workshop and he claimed that something was wrong with my car and that point I had already paid them and received an invoice with a 3 months warranty. So I then tried to explain to the guy about couple of days after but he told me that he will do it in January since it’s the holiday season he doesn’t have manpower to fix my problem then I asked what if I find someone who can check the car on my side and fix the issues of the car not seeing the unit I bought from him he hesitated saying he will call me later. He then called later telling me that I should buy the key control unit that came with this unit I bought I then refused because the one I have had no problem but it was his part of his service to align the key control unit with the unit I bought from him. So I waited for holidays to pass then I contacted him to check his availability and I battled but in the meantime I asked another technician to the problem and they found was that my car doesn’t see the unit that I bought and I paid that guy for diagnosing. I then called the guy who bought me this unit with better luck I find him but we didn’t speak long and the call canceled but he called back then I cannot hear what he was saying then I tried calling him several times but the call didn’t go through. I ended texting him notifying him that I will come to his workshop to deliver his unit and get my money because this deal is causing me stress than solutions but even that text didn’t go through it came back to my outbox. I then went to his regardless I find the consultant lady and she told me that guy was out of the country hence his phone signal was problematic. I told that lady to notify him that I wanted out of this deal and she gave their business card because on their website it showing the owner’s contact only. That lady then contacted me to me that this guy is back and I tried calling him but the phone was answered by his so called business part and we never got anywhere because that partner **** and I was furious because I did called their workshop before calling his cellphone. I then the following day to schedule an appointment of which I still have to honor it but I had already told the consultant that I want my money that’s all.