The answer to this depends so much upon why the customers are dissatisfied in the first place. In general, what the company will need to do is to look like it is fixing the problem that made the customer unhappy. If this is not possible, the company at least needs to show that it is concerned about the customer’s unhappiness and is doing what is possible to make amends.
The best way to regain customers’ satisfaction is to fix the problem with your company. If a customer is unhappy about the service at your store, hire better workers. If a customer is unhappy with your product, make a product that they will like. If a customer feels that the food they ordered from your restaurant is not good enough, give them a free dinner. Customers will generally be satisfied if a company fixes the problem that is bothering them.
Of course, not all problems are easily fixed in a short time frame. Volkswagen, for example, has no quick way to fix the damage that the recent scandal about gas mileage has done to their reputation. BP cannot easily fix its reputation after its disaster in the Gulf of Mexico. In such cases, all a company can do is to show that it is working as hard as it can to fix its problems and that it is willing to do what it can to make customers whole. Sometimes, this will take the form of monetary compensation. For example, if you cater someone’s wedding and something goes wrong with the food, there is nothing you can do to truly make up for spoiling their event. All you can do is to show how sorry you are by refunding a substantial portion of their money. This will not fix the problem, but it will at least show the customer that you are acting in good faith and that you understand and regret the problems that your company caused.
In short, the best way to regain satisfaction is to fix the problem that caused customers to be dissatisfied. If this is not possible, you have to at least show that you care and that you are doing everything you can to make sure a similar problem does not occur in the future.