Law question: I was involved in a car accident in a shopping centre?

Black Ice is considered an expected hazard, i.e. if conditions are wet and the temperature is close to or below freezing, drivers are expected to be aware that black ice can occur and drive appropriately. There is no requirement for any warning. The center is required to take reasonable care to clear the lot, but they are not expected (nor able) to clear every patch of ice or snow. Basically, you can take it to court, but your odds of winning would be extremely low, and there's a good chance the center would counter-sue for costs. Unless you have proof of negligence, you don't have a case.

You were driving too fast for conditions. If your insurance company feels that the accident was the fault of the property owner, they will sue for you. Send them a copy of the police report.