SMG NORTH COAST POOR WORKMANSHIP

Good day I had my BMW at SMG north coast to replace an injecter the bill was close to R24000, they towed my BMW, the diesel came out the car like an river after getring it back,messing out my whole tank of diesel, my towing cover is gone...my cup holder is broken, my whole driveway is full of diesel and I sold the property this costs of cleaning and fixing my car will be for SMG North coast... what if my car burned ??? The deal principal blocked me an their whatsapp line... I have the proof... she has an bad attitude and told me she will not entertain my threats... there was no threats but merly an attempt to fix their poor work performance... all the diesel went into all my suspention rubbers... engin mountings etc and that will cause the rubbers to soften.... Where to now ???