Over the past few years, the digital high street has become a bustling hub of commerce. E-commerce sites, while offering unparalleled convenience, also grapple with an intricate web of customer complaints and return requests. 

Navigating these challenges can be tricky, but online retailers can ensure seamless operations and elevated customer satisfaction with the right strategies.

1. Understanding the Nature of Complaints:

Before diving into resolutions, it's crucial to understand the very nature of the complaints. Do they stem from product quality, delivery, or website usability issues?

• Detailed Feedback: Encourage customers to provide detailed feedback. This aids in pinpointing the root causes of grievances.

• Data Analysis: Use analytics to identify patterns. For instance, if a particular product receives consistent negative feedback, it might be worth delving into its quality or description accuracy.

2. Building a Robust Investigation Framework:

Having a structured approach is crucial. This means clear guidelines for your customer service team, ensuring consistency.

• Timely Response: Aim to acknowledge complaints within 24 hours. This immediate recognition can go a long way in assuaging disgruntled customers.

• Empower Your Team: Provide adequate training and autonomy to your customer service team, allowing them to address issues efficiently.

• Transparent Communication: Always keep the customer in the loop. Regular updates about the status of their complaint can foster trust.

3. Returns Management: Striking a Balance:

While often viewed as a hassle, returns are integral to online shopping. Here's how to manage them effectively:

• Clear Returns Policy: Ensure your return policy is fair and transparent. Highlight conditions like the 'return window' or any product-specific stipulations.

• Easy Process: Use a straightforward returns process. Consider prepaid return labels, drop-off points, or even doorstep collections where feasible.

• Quality Control: Before restocking returned items, ensure they undergo rigorous quality checks.

• Feedback Loop: Whenever a product is returned, capture the reason. This feedback is gold for improving future operations.

4. Leveraging Technology:

Embrace technology to streamline complaint and return processes.

• Chatbots & AI: Use AI-driven tools to solve common queries instantly. While they can't replace the human touch, they can undoubtedly augment it.

• Integrated Systems: Employ integrated Customer Relationship Management (CRM) and inventory systems. This can help track complaints and returns, ensuring nothing slips through the cracks.

5. The Human Touch:

Amid all the processes and technology, never underestimate the power of empathy.

• Active Listening: Sometimes, customers just want to be heard. Train your team in the art of active listening.

• Go the Extra Mile: Whether it's a goodwill gesture like a discount on the next purchase or a handwritten apology note, these small touches can make a difference.

As the digital marketplace evolves, so do the challenges e-commerce sites face. However, these challenges can be transformed into opportunities with meticulous planning, embracing technology, and maintaining the age-old virtues of empathy and understanding. 

After all, every complaint addressed is a lesson learnt, and every successful return management is a step closer to unparalleled customer loyalty.