Disappointment with the Service and Treatment

On the 9 December 2022, I went to put in Diesel at Shell Melville, The attendant's attention wasn't on me as he was chatting up a lady and talking to the other attendants. I asked him to put R200 Diesel and went into the shop to purchase a ****in. I paid for both my Diesel and my purchase. On my way home my engine cut out totally and my car stopped. At the time I thought it was my remote. But then opened my flap and if you open my flap you can see in bold letters and yellow it says Diesel. I then phoned the manger who wasn't there but explained my situation to his wife who said they will reimburse me. Her husband the manager phoned me back but was very rude and had no intention of reimbursing me. I have all the facts and receipts and statements. Photo's of what was drained from my car. I phoned and spoke to him again and still insisting it needs to be investigated. What investigate if you have all facts and can't admit to your fault. I have heard from a few people who the same thing happened to but at different garages they where treated with respect and cars fixed up. This gentleman has literally put the blame onto me. But if his attendant opened the flap and saw diesel and I did say petrol would you not have waited for me to come out and ask. I am a pensioner and from the 9 December until now have not have the use of my car, which is shocking to say the least.