Very Unhappy!

Hi, i am Amelia... On 17/9/2018 i fitted a new exhaust system with noise boys pretoria north branch. Sinse a day after it was done my car made a backfire sound and could hear somethings up. But i work shifts and can only do so when i am off on a monday. So today is my off day, decided to go to De Graafs in pretoria north, to just have a second opinion before i go back to noise boys... And De Graafs said its leaking and or there must be a hole somewhere. So i went to noise boys. Went to the office, the guy infront were on the phone, as i greated him and waited for him to get of the phone, when he did i said i fitted a new exhaust here and can you please check what **** they did with the exhaust, i also said i just come from De Graafs as i went for a second opinion first... So he said i must pull the car on the ramp and i did so then he said we must wait for some guy to come back... So we waited, when this man arrived this front desk man"there boss" told him that i am complaining about something sucking air and de graafs said it must be the exhaust. So this appy walk to my car open the bonnet and wana look for the fault there, and i said hey what do you wana do in the bonnet, the engine has got nothing to do with the exhaust... So he go a serious attitude, jump in my car and start it, so i knocked on the window, the opend the door i asked hom where you going, said he was gonna go around the block, so i said please dont drive the *** out of my car, and he stripped his moer jumep out of the car, said to me, you go fix your own car. I said, askies... And he went into the front office and told his boss he wont help me and argue with me about my airfilter in the engine thats sucking air. So i told them, the engine has got nothing to do with the exhaust... Anyway, so the boss and myself yelling in screaming he hit my car with his hand and told me to leave and told the african workers, sien julle n ding soos die is wit gemors. So i went back to de graafs and asked him to lift the car so i can take pictures of where the issue is, and i did so. So i went back to noise boys to show him on the exhaust where the problem is... He had a *** attitude, and by then i did too...i walked in and said it doesnt help cos you having a *** day take it out on your customers and do as you please, here are the photos. So i put my car on the ramp, i asked whos gonna work on my car... Sam i think his name is... Who did the exhaust in the first place where told to do it... So it turned out he had to replace the new 2nd box and when he did so, the worker cutted thin pipe bits and welded that onto the box before welding it to the pipe. So it doesnt look well for a brand new complete exhaust like that, so i went to ask the boss is this right and doest all that welding going to make it fragile....but his 2 white guys where in the office with him, they watched the security video off their shop to wana make as if its me who has a *** attitude and it went so far as the one white worker said to his boss while i was outside that he will give me a **** klap... So i went in and said excuse me, who do you think you are, so he says to me, hy sal my n **** klap gee lat ek wens ek was eder n vrou, cos i am *******. I ask him to please lift his hands i beg him, so he started telling me in his eyes i am a child and a *******... He will hit me he knows lawyers. I want to know what to do, i am not happy with this exhaust, he doesnt want to take it off give my money back so i can go elswhere, where i surely will be treated better if the company's at fault and the customer sees no point in being in my engine if the exhaust sits underneath my car?