The retail industry is responsible for 1 in 4 American jobs, according to the National Retail Federation. That's spread across 3,793,621 retail establishments accounting for $2.6 trillion in total global domestic product in the U.S, based on the most recent NRF reporting.

With such a vast number of retail transactions occurring on a daily basis, both online and in stores, it's hardly surprising this industry faces its fair share of customer complaints. While complaints themselves come in various shapes and sizes, they generally fall into one of five categories:

1. Negative Interactions

Negative retail interactions typically concern customers complaining about less-than-satisfactory experiences with employees. This can take the form of a sales associate being rude or even a lack of attention from employees altogether. Retail companies that depend on phone and chat support for their online counterparts may also receive complaints regarding unhelpful or ill-mannered staff.

2. Billing Issues

Inaccurate and multiple charges, pricing mistakes and failure to implement coupons, sales codes and consumer rewards all fall under the umbrella of billing issues. Billing complaints tend to be among the most severe, as they directly relate to customers' finances.

Billing complaints can be fierce since they affect customersBilling complaints can be fierce since they affect customers' pocketbooks.

3. E-commerce Problems

The growth of internet usage has transformed the retail industry in the form of e-commerce. Data compiled by Statista showed that in 2017, 1.77 billion people worldwide are expected to purchase goods and services online, with the number forecast to grow exponentially from there. This has led to a marked uptick in customer complaints associated with ordering errors and shipping mistakes. In short, the more orders pouring in, the greater the likelihood for a package to end up in the wrong location.

4. Refunds

Closely linked to billing issues, refunds are another area where customers can easily become upset. If there is confusion regarding return policies, or refunds are inaccurate, retail businesses can count on unhappy customers. This is especially troublesome, as customers seeking refunds are already more likely to be unhappy with a business. Problems with returns only exacerbate the situation.

5. Product Quality

Complaints relating to product quality can come in one of two forms: Either disappointment with the quality of a product itself or damage incurred by a product in the course of its delivery. Either way, customers are likely to complain to businesses themselves, their social circles and online review websites.

"Retail volume essentially guarantees customer complaints."

Solving Retail Customer Complaints

No matter how hard businesses try, the sheer volume of retail interactions all but guarantees customer complaints will occur from time to time. The key is responding to these grievances in an efficient, effective manner.

Resolution of customer complaints is inextricably linked to customer service, and a majority of consumers (76 percent) associate customer service with how much a business truly values them, according to a report from Aspect Software.

This is especially important in the eyes of millennials, who recently overtook baby boomers to become America's largest generation.

"As millennials are more 'experience-loyal' than 'brand-loyal,' consumer engagement is quickly becoming a far more influential factor in building positive brand perception," said Joe Gagnon, senior vice president and general manager of cloud solutions at Aspect Software. "It's imperative that businesses adapt their customer service strategies to deliver an interaction strategy that addresses millennial engagement preferences."

If engagement is the goal, time is of the essence. This makes it vital for retail businesses to have systems in place to quickly and easily track customer complaints.

Issue tracking software allows retailers to enhance customer support through complaint management, flagging issues with the proper individuals. If complaints are left to fester without resolution, retailers will find themselves becoming part of the $83 billion a year lost due to bad customer service.

Whether it's in the form of abandoned online shopping carts or in-store customer churn, data shows it pays to understand what complaints are most common among retail shoppers, and to invest in tools that make solving these issues easier.