What's causing the sudden increase in failed transactions for Monzo's virtual card payments?

Introduction

The sudden increase in failed transactions for Monzo's virtual card payments is a critical issue that demands immediate attention. This problem directly impacts user experience, revenue, and trust in our digital banking platform. I'll approach this analysis systematically, focusing on identifying the root cause, validating hypotheses, and developing both short-term fixes and long-term solutions.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this might be related to a recent system update. Has there been any significant change to our payment processing infrastructure in the last few weeks?

Why it matters: System changes often correlate with performance issues. Expected answer: Yes, a new payment gateway was implemented two weeks ago. Impact on approach: If confirmed, we'd focus on the new system's integration and performance.

• Considering user segments, I'm wondering if this is affecting all users equally. Are we seeing a higher failure rate for any particular user group or transaction type?

Why it matters: Helps narrow down potential causes and affected areas. Expected answer: Higher failure rates for international transactions. Impact on approach: We'd investigate international payment processing specifically.

• Given the nature of virtual cards, I'm curious about the security measures. Have we recently updated our fraud detection algorithms or security protocols?

Why it matters: Overzealous security measures can lead to false positives and failed transactions. Expected answer: A new fraud detection system was implemented last month. Impact on approach: We'd examine the new system's rules and thresholds.

• Thinking about external factors, I'm considering if there have been any changes in our partnerships or integrations. Have we onboarded any new merchants or changed our relationship with existing payment processors?

Why it matters: Changes in partnerships can affect transaction success rates. Expected answer: No significant changes in partnerships. Impact on approach: We'd focus more on internal factors if this is ruled out.