Most of the haccp/iso 22000 trainers/consultants use the concept "farm to fork/plate". this thought is wrong in the restaurants who directly distribute the hot meal boxes within the restaurants.
What precautions to be taken by the restaurants to avoid any legal cases, if the customers report any food poison cases?
You define the scope of your haccp plan so in the case of a takeaway restaurant, it is from the receipt of ingredients to serving the consumer. If consultants / trainers feel that there is a need to check the temperature of your customers food every hour after purchase then they need a reality check......or have I misunderstood you!
If you can prove that all precautions were taken whilst the food was under your control, then I don't see a problem. As I said before, once it is with the consumer, there isn't much you can do.