The proposed £15 billion merger between Vodafone and Three UK faces significant regulatory challenges from the UK's Competition and Markets Authority (CMA). The CMA's provisional findings suggest the merger could lead to higher prices and reduced services for millions of mobile customers, especially affecting those least able to afford mobile services. The reduction in the number of major telecom operators from four to three could also limit competitive options for smaller telecom firms and Mobile Virtual Network Operators (MVNOs). Despite Vodafone and Three's commitment to invest £11 billion in digital infrastructure, the CMA remains skeptical about the promised network improvements and investment follow-through. The CMA is considering potential remedies, including forcing the sale of assets or spectrum to ease competition concerns. A final decision on the merger is expected by December 7.