Engine contamination by shell protea glen

I am laying a complaint against Shell Protea Glen. On the 30th July 2022 I went to fill diesel but a negligent petrol attendent poured petrol instead this resulted in my car engine being damaged and was taken by Shell mechanic Denver based in Midrand. We were then advised to send documents which included a letter of demand, drivers Licence, vehicle documentation which was all sent. I have been getting a run around from Shell regarding how my vehicle will be fixed to a point where i had to drive to Midrand from soweto to see the mechanic only to find a quotation of second hand engine cost R19000 I spoke to the mechanic who was oblivious to my concerns and the fact that my vehicle is a business vehicle and money is being lost. I questioned as to how insurance can say they will pay out in second hand goods and what guarantee do I have that the second hand engine is not going to give me any problems, the mechanic could not guarantee. I furthermore went back to shell and requested to speak to the owner of which Joe Bishop was contacted but he advised to write everything down for him on email which not even once has he responded then the broker Dion called me to advised me that they will send R28000 which was the quoted amount by the mechanic Denver who we advised we want nothing to do with and he furthermore said we can take Shell to court should we please. My biggest complaint is how shell is giving me a runaround while my source of income is with them. I have lost clients due to the fact that I can't deliver because my vehicle is damaged and my family is suffering financially. Shell is not even will to compensate me my loss and still want to erect a second engine which might furthermore put my business in danger since there is no guarantee, if it's a good engine. I need assistance as to how to handle this because I feel Shell is not taking me serious, and we can not settle for a second hand engine which does not have guarantee.