Unresolved fuel contamination situation

I would like to share my disappointment with BP in cascades, Pietermaritsburg. On the 26th of August at around 19:30 I asked for R500 diesel, I then paid for the diesel and went home which is about another 50km. As I parked the vehicle I noticed a misfire when idling. A few days later I took the bakkie to my nearest Toyota dealership and did a diagnostics test and found 2 injectors to be failing as well as diesel pump pressure that was out of spec. Upon further investigation we found Petrol contamination in my diesel tank and I contacted BP in cascades immediately. The owner, Mrs Sokhela, answered and promised to investigate further the next day. After multiple phone calls back and forth she told me that Petrol was put in my vehicle and she asked if her mechanic could repair the vehicle, I insisted on someone who is RMI approved and is actually qualified to perform such repairs. She told me she will further investigate the situation and get back to me. I then received another call from the owner and she admitted that it was on camera and after investigating with her staff that worked that evening, she found that the attendant put R250 petrol, realised he was making a mistake and then changed to diesel without me noticing and not saying anything, this is what the attendant had also admitted. Mrs Sokhela also stated that what she can see on the cameras also matches the payments made as the attendant paid for the R250 petrol with his own card. After she had told me this I asked for it writing that I can send my vehicle to Toyota to be repaired and the costs will be covered by BP Cascades or their insurance. Mrs Sokhela's attitude to the situation was extremely unprofessional and she refused to give me anything in writing only giving me her word which I believe is not good enough. I am now left with no choice but to seek legal action as the quote I have received from Toyota is around R52000 and I do not believe that I should be held responsible for the negligence and dishonesty of one of BPs employees. I am hoping that BP will take action on this matter as its becoming a major inconvenience and I'm disgusted by the interaction I have received by the owner. Thank you