Pioneer Credit's one-time white knight, private equity firm The Carlyle Group, has accused the struggling debt buyer of a series of defaults under a facility agreement and is threatening to demand repayment of A$141.6 million.Carlyle emerged in December as a buyer of Pioneer, which is struggling to manage debt covenant breaches, defaults and a looming refinancing deadline. The parties entered into a scheme implementation agreement and a funding agreement.Last month, the deal started to come undone. Pioneer issued a statement on March 24 saying that, following a request that Carlyle proceed to finalise lodgement of the scheme booklet with the relevant authorities, it received a letter from Carlyle requesting further information in relation to Pioneer's business operations and performance.In the latest update, Pioneer said it received a letter from Carlyle alleging "a number of defaults have occurred and are continuing under the facility agreement."The alleged defaults include a material adverse effect as a result of the impact of COVID-19, non-compliant disclosure of information, non-lodgement of a compliance certificate and cross defaults under medium-term notes.Pioneer has lost some senior management, most recently its chief financial officer, and this is reported to have been received badly by Carlyle.Carlyle has not made a demand for its money yet.Pioneer said it "refutes all of Carlyle's claims and believes that none of the matters cited in support of the allegations comprise a default under the facility agreement or, by extension, the medium-term notes."Pioneer said it has requested that Carlyle withdraw its default notice by Friday and threatened to commence legal proceedings if it is not withdrawn.Pioneer's problems go back to an accounting change in the 2018/19 financial year. There was a material difference in its expected net profit for 2018/19 due to the classification and measurement of its financial assets at amortised cost.The application of amortised cost to more than 900 debt portfolios changed the timing of when earnings are recognised in the accounts. The change explained the fall in earnings from $17.6 million in 2017/18 to $4.3 million for the year to June.The fall in earnings triggered a breach of the company's financial covenants under its senior financing facility.In September, the company reported that events of default had occurred and that it had entered into a standstill agreement with its senior financiers, Bankwest and Westpac.The funding issues had a negative impact on the business. It struggled during the December half, largely because of constraints imposed on financing activity follow the covenant breach. It has also incurred significant costs under the standstill agreement with its lenders and also the cost of conducting the change of control process.The company made a loss of $8.7 million for the half-year, compared with a profit of $3.7 million in the previous corresponding period.Pioneer said yesterday: "It seems clear to the board that Carlyle is intent on exercising maximum pressure on the company, including using the potential impacts of COVID-19 to move from its original commitment under the scheme implementation agreement and either withdraw from the transaction or attempt to