DA leader Mmusi Maimane has threatened legal action against President Cyril Ramaphosa if he fails to respond about a letter in which the ANC is alleged to have thanked Bosasa - now trading as African Global Operations (AGO) - for a R3m donation.In a letter dated September 20 and addressed to Ramaphosa - which News24 has seen - Maimane asks the president to urgently respond, or "[the DA] will pursue this matter legally". News24 previously reported that, on March 31, 2014, then ANC treasurer general Zweli Mkhize thanked Bosasa former CEO Gavin Watson for a R3m donation to the governing party.On August 22 this year, Maimane handed a copy of Mkhize's letter to Ramaphosa in Parliament, asking him what Mkhize meant by the "continued financial support" from Bosasa.He also asked whether Ramaphosa would commit to ensure that the governing party repays to the fiscus all the money received from Bosasa from the past 15 years.Ramaphosa said he would study the letter and respond to Maimane later. But more than one month later, the president has not responded, says the DA. READ: Public Protector finds Ramaphosa 'deliberately misled' Parliament over R500 000 Bosasa payment"This is a very serious matter of accountability where many of these matters dealing with Bosasa have been discussed at the Zondo Commission of Inquiry into State Capture and where I have raised this issue with the Independent Electoral Commission," Maimane writes in his September 20 letter to Ramaphosa."You would be criminally liable if you and your party knew and benefited from the proceeds of crime," the leader of the opposition adds.'President continues to be unaccountable to Parliament'He said National Assembly Speaker Thandi Modise had indicated in a separate letter to the DA that she had written to Ramaphosa to remind him of his undertaking in the House that he would get back to the DA.Maimane's spokesperson, Azola Mboniswa, told News24 that the president had taken more than a month to "reflect" on the letter."This shows that the president continues to be unaccountable to Parliament over the most serious issue facing his Presidency. DA leader Mmusi Maimane requests an urgent update on the R3m 'donation' from Bosasa to the ANC," Mboniswa said.Corruption allegations against Bosasa have dogged the company for over a decade, with a string of claims alleging the firm bribed government officials and politicians to secure multimillion-rand tenders.In 2009, the National Prosecuting Authority announced that it had received a report into corruption between Bosasa and the Department of Correctional Services and had handed it to the Hawks for further investigation.Former Bosasa chief operations officer, turned whistleblower, Angelo Agrizzi testified at the state capture inquiry that the company had supported the ANC financially for many years, as News24 reported.The company's campus in Krugersdorp was used as a "war room" by the ANC during the 2014 and 2016 elections.Several attempts to contact Ramaphosa's spokesperson, Khusela Diko, were unsuccessful. Once comment is received it will be included and the report updated.