Counter lawsuit could cost Sandilands and Henderson millions.

and could be out of pocket to the tune of millions of dollars, thanks to a new countersuit by their former employers.

The Commonwealth Broadcasting Corporation (CBC), a subsidiary of ARN Media that runs KIIS FM, has filed a countersuit against the former breakfast duo.

They are reportedly demanding that Henderson and Sandilands pay for advertising revenue KIIS lost after the pair allegedly breached their $200million, 10-year contracts, according to the Morning Herald.

It was also reported that CBC is demanding Henderson and Sandilands pay legal costs as well as vigorously defending claims made by the pair.

Court documents, lodged this week, allege that Henderson and Sandilands cost the radio station both advertising revenue and profits by breaching their contracts.

It was also claimed that a clause in ARN's services agreement with Sandilands' Quasar Media allows it to reclaim 87.92 per cent of a $3million signing bonus.

This means that Quasar Media – the company through which Sandilands provided his services for The Kyle & Jackie O Show – could have to repay $2,637,600.

It comes as shock new details emerged about the explosive fallout between Sandilands and Henderson this week, with court documents alleging he told her to 'get your f***ing s**t together' or 'don't f***ing bother coming back'.

The alleged outburst took place during a fiery off‑air clash months before the pair's infamous on‑air bust‑up - which ultimately brought their hit breakfast show crashing down.

According to documents filed in the Federal Court late Tuesday, the confrontation unfolded at KIIS FM's Sydney studios following an incident broadcast on air last year.

The court documents, lodged by CBC, allege that the once rock‑solid friendship – forged over more than 20 years on air – had already fractured months earlier, with a massive behind‑the‑scenes blow‑up in September last year.

CBC alleges Sandilands spoke 'contemptuously' to Henderson during an on‑air argument - an incident she has also cited in her statement of claim against the network.

But the argument didn't stop when the microphones were switched off.

'Kyle, that's a bit rough, like f***en hell, I haven't done anything to f***en cop it,' Henderson is alleged to have said, according to CBC's defence documents.

This means that Quasar Media – the company through which Sandilands provided his services for the Kyle & Jackie O Show – could have to repay $2,637,600