Verizon Wireless sent the FCC a 14-page screed on Wednesday denouncing critics of its AWS purchase to "address a litany of erroneous claims" from T-Mobile USA and a number of other groups.

The missive was posted the day after the Commission decided to extend its review of the deal by three weeks after it received complaints that Verizon and the other companies in the transaction had missed deadlines for producing documents and made some files available in an inaccessible software format.

"A few parties continue to repeat claims that have no merit," Verizon said in a letter, also signed by the cable companies it is purchasing the AWS spectrum from – Cox Communications, Time Warner Cable, Comcast and Bright House Networks.

In its latest defense of the $3.9 billion spectrum sale, Verizon singled out T-Mobile and the Rural Cellular Association for criticism, stating the FCC could not legally block the sale so that others could purchase the airwaves, as it said they have suggested.

Verizon rebutted allegations that it has warehoused its spectrum and didn't use its spectrum assets efficiently, stating that it has "devoted significant time, effort and millions of dollars of expense to clearing its existing AWS spectrum" and will sell off its unused 700 MHz A- and B-block licenses if the government approves its AWS purchase.

Opponents to Verizon's acquisition of the nationwide swath of spectrum have lodged a number of complaints about the deal, principally that it will harm competition by consolidating too many licenses in the hands of a single provider. Verizon denied the claim in its letter, referring to the abundance of licenses held by Clearwire, and pointed out that the AWS sale will not remove competitors from the marketplace.

Verizon has stepped up its efforts to get the AWS sale approved in recent weeks, dredging up comments T-Mobile made during the AT&T merger to cast doubt on its opposition and offering to sell off some of its valuable 700 MHz assets if the AWS deal goes through.

The FCC's decision Tuesday to add 21 days onto the transaction's review marked a minor setback for Verizon, which now expects the deal to close in late summer instead of mid-summer.