Water cap not put back

I'm really disappointed by the service that I received at the new Caltex in Edenvale, Van Riebeeck road next to KFC. I went there after work on Thursday 27 August and asked the petrol attendant to check my water and oil. I left afterwards, I didn't see a need for me to check if all was in order. After about 4 km on the road my wind screen was filled with steam coming from the bonnet it was weird because I had never experienced that. When I got home I found that my water cap wasn't put back. I could not use the car the next day.I called Caltex & spoke to Imo n asked to view footage. In the footage it showed that the attendant didn't put the cap back but left it on the engine box.I was really disappointed by what I saw n da possible damage to my car. Imo asked me to check in da car again n promised to replace it if I don't find it. On Saturday Imo called n said someone found my cap n dat I must come collect it. When I got home da cap wasn't da right size and possibly belongs to someone else who experienced the same service like me. This is a disgrace if it's the culture of Caltex, and motorists have to suffer the costs because someone was negligence.