Sears Auto Center

I went to get an oil change. 20 minutes later they called and told me they were couldnt do my car. The oil was low but there was a little on the dipstick. They claim there was no oil. When I receive the car the oil cap was on the ground. When I called customer service they said that it was policy if there was no oil in the car they couldn't change the oil. But there was a little on the dipstick. And still refuse to report a complaint. even know they forgot to put the cap back on. If I had not seen that it would've only been worse and they would not have taken blame