Angola’s state oil company Sonangol has amassed hundreds of millions of dollars in debts and deferred payments to oil majors and contractors while its new chief, Isabel dos Santos, attempts to reform its operations, Reuters reported.

Its is reported that Sonangol owes money to oil majors Chevron, Total, BP, ENI, and ExxonMobil, with Chevron demanding $300m in unpaid cash calls. Dos Santos said that the company needs to undergo financial restructuring and $1.569b to guarantee payments until the end of this year, Macauhub informed. She added that revenues from Sonangol have been falling since 2013 “without operating costs falling in line with this drop. Furthermore, she estimates gross revenues of $15.325b, with the company withholding from paying dividends to the State.

Contractors say they have waited months even for small payments from Sonangol, which handles the oil and gas reserves of Africa’s second-largest oil exporter. The delays began following the appointment of dos Santos in June to root out waste and corruption at a company that was struggling even before oil prices plunged.