Story highlights Whitefish Energy's contract is up on December 1

The company says it is stopping work before then because it is owed millions of dollars

San Juan, Puerto Rico (CNN) Whitefish Energy is stopping its work to restore Puerto Rico's broken electricity grid because the company says it is owed more than $83 million by the island's power authority.

Whitefish CEO Andy Techmanski told CNN that repeated requests for agreed payments were not met and there was no choice but to suspend work.

He claimed credit for the restoration of transmission lines by his contractors, even after his company's controversial contract with the Puerto Rico Electric Power Authority (PREPA) was set to be voided.

"We stopped because of the financial situation, lack of payment with PREPA has gotten beyond its maximum threshold and what we can sustain as a business," he said.

A letter sent by Whitefish to PREPA and seen by CNN accuses PREPA of delaying payments. As of Sunday, Whitefish said $83,036,305.09 was outstanding, including more than $26 million that it said had been audited and approved by PREPA already. Without payment to Whitefish, contractors and subcontractors were also going unpaid, the letter said.