What can you do if your employees frequently have to deal with angry customers, through no fault of their own? It's one thing to motivate employees under pleasant circumstances, and even that isn't all that easy. But keeping them motivated and doing a great job when they're getting an earful from customers on a regular basis is a whole different matter. As a manager, you want to support them while still meeting the constraints that make the customers angry in the first place.
Identify the root cause(s) of the complaints.
The first step is to get more information about why there is a consistent pattern of dissatisfaction. Are customers mad about not being able to get deliveries in time for a major holiday? Do they call expecting to get the great new rates advertised for new customers, only to find that they're ineligible because they already have an account? Maybe they're mad because they're not allowed to do something that could be a safety concern. Whatever it is, find the underlying reason for that issue. A tool called the Five Whys can be helpful in cases like this. Keep asking "Why?" until you get to the true root of the situation.
Make sure the situation is unchangeable.
If customers are consistently making the same complaint, it's worth looking at whether anything can be done to fix the underlying issue. For example, if customers keep asking to be able to do something that is viewed as a potential liability issue for your company, is there a waiver that would put company lawyers at ease and enable customers to take on the risk themselves? Could the new customer rate be offered to any existing customers who commit to a yearlong contract? Could an alternative shipper be used, with the extra costs for expedited delivery paid by the customers? In a lot of cases, you may be too far down the corporate food chain to be able to change a particular policy or practice, but it's worth at least exploring. At the very least, your employees will be more willing to deal with the situation if they know you've tried everything you can to mitigate it for them.
Help your employees to feel less powerless.
Dealing with an upset customer is really stressful, and when both the cause and any potential solutions are out of your hands, it's outright demoralizing. You can help your employees reframe the situation by acknowledging that the situation is inherently frustrating, and encourage them to think of creative ways to help customers have a more positive experience given the constraints. What can be done to make the customer's experience less frustrating (and therefore less unpleasant for the employee trying to help)? In some cases, there might be procedural solutions like making sure people know about potential restrictions up front, but in most cases it will be more about how the employee interacts with the customer.
At the very least, make sure they avoid using trigger phrases like "it's in the terms of your contract" or "that's the policy." Help employees understand that the same exact information can be delivered in a negative, restrictive way or a positive, welcoming way. "We don't have any appointments available until Friday" is the exact same information as "I can get you something as early as Friday."
Make sure your employees know the reasons behind things so that they can provide context to the customer. That won't always work, but in a surprising number of cases, just having a rationale, any rationale, will help defuse a person's anger.
Balance empathy with toeing the company line.
With all of these strategies, the key is to make sure the employee is balancing support for the customer with representing the organization effectively. It's not good customer service to agree that "yeah, our policies suck!" You can model this for your employees by balancing your support and empathy for them and their frustrations with the organization's reasoning and priorities. Help them to focus on the positive, and who knows - maybe together you'll be able to come up with a way to have fewer unhappy customers altogether.