Arnold Chatz Constantia Poor service!

I took my Jeep Renegade in for a service on 21/02/2018 and about a day after that the "check engine oil" light came on so i went back to Jeep Constantia (Arnold Chats) and a technician reset the settings, however, the "check engine oil" is still warning me which makes me wonder whether the oil was even changed when my car was in for it's first service. I am very disapointed in the service from Arnold Chats and this is totally unacceptable.