Vodafone and Three have hit back at the UK Competition and Markets Authority (CMA) over the regulator's provisional findings into its £15 billion ($19bn) merger.

The CMA revealed earlier this month that its investigation, led by an independent inquiry group, has "provisionally concluded that the merger would lead to price increases for tens of millions of mobile customers, or see customers get a reduced service such as smaller data packages in their contracts."

On top of that, the CMA stated that the merger would negatively impact ‘wholesale’ telecoms customers – mobile virtual network operators (MVNOs) such as Lyca Mobile, Sky Mobile, and Lebara. All three of these MVNOs rely on existing network operators to provide their own mobile services.

In response to those findings, Vodafone and Three today (September 30) issued a joint statement that said the merger would prove to be "pro-growth, pro-customer, pro-investment, and pro-competition" for the UK.

Vodafone and Three claim to have made two substantive commitments to ensure the CMA approves the deal. One of those includes selling spectrum to rival telco Virgin Media O2 once the merger is cleared, a company which it signed a decade-long network sharing deal in June.

The other is to invest £11bn ($14.73bn) into its digital infrastructure in the UK.

The duo also disagreed with the CMA that its merger would lead to price increases, noting that it will maintain tariffs at £10 ($13.39) for two years from the completion of the deal for some of its MVNOs, including Smarty and Voxi.

"The merger of Vodafone and Three is a catalyst for change," said the two companies. "It will deliver a step-change in connectivity to UK customers and bring best-in-class 5G to every school and hospital in the country.

"Transforming the UK’s digital infrastructure is also vitally important for businesses, the public sector, the UK’s technological advancement, and the government’s stated mission to kickstart economic growth."

The CMA launched its Phase 2 investigation into the merger, which is poised to create the UK's biggest mobile network operator, back in April, before extending the deadline for a decision on the merger until December 7.