T-Mobile CEO John Legere is ramping up pressure on the Federal Communications Commission to approve his company’s merger with Sprint.

The bombastic CEO pledged not to increase rates for customers for the first three years post-merger in a letter to FCC Chairman Ajit Pai Monday.

“To remove any remaining doubt or concerns about New T-Mobile’s prices while we are combining our networks over the next three years, T-Mobile today is submitting to the Commission a commitment that I stand behind – a commitment that New T-Mobile will make available the same or better rate plans for our services as those offered today by T-Mobile or Sprint,” Legere wrote.

T-Mobile and Sprint have been making the case for their merger, which needs federal approval, for months. They claim the deal will allow them to better compete with industry titans AT&T and Verizon and catalyze American leadership in the development of 5G wireless technology.

“If we broke faith by raising rates and cutting back benefits, we would lose our loyal customers and destroy the future of our brand,” Legere wrote. “I want to assure you that we would never do this.”

The companies have also retained former FCC commissioner Mignon Clyburn to advise them on the merger, according to The Hill.

Last spring, T-Mobile and Sprint agreed to merge and create a $146 billion company called simply, T-Mobile. The consolidated company’s primary headquarters would be in T-Mobile’s hometown, Bellevue, Wash., with another office in Sprint’s home of Overland Park, Kan.

T-Mobile also said today it plans to locate the second of five New T-Mobile Customer Experience Centers in the Rochester, N.Y. T-Mobile said the new customer service center will bring 1,000 jobs to the area. The company previously announced plans for a customer service center in Sprint’s hometown of Overland Park as well as commitments to expand a couple other existing facilities.