Dimitri Payet’s agent has refused to comment on reports Marseille will meet West Ham officials this week to discuss his transfer, with the France international’s future in the Premier League looking increasingly doubtful.

Payet was left out of West Ham’s 3-0 victory against Crystal Palace after informing his manager, Slaven Bilic, that he wishes to leave the club. Writing in his matchday programme notes on Saturday the West Ham co-chairman David Sullivan insisted the 29-year-old would not be allowed to leave this month, although it is understood the notes were written on Thursday and his attitude has since softened.

The vice-chairman, Karren Brady, also conceded on Saturday in her column for the Sun that “probably sooner rather than later he will be on his way”, while the co‑chairman David Gold has also admitted privately that Payet is expected to move back to Marseille partly because of his family’s unhappiness with life in London.

It is believed West Ham would be willing to sell if they receive an offer of about £30m and reports in France on Sunday claimed West Ham officials will meet the Marseille president, Jacques-Henri Eyraud, on Monday to discuss the transfer, although the player’s long‑term adviser Jacques-Olivier Auguste refused to confirm that when contacted by the Guardian.

Payet, who signed a bumper £125,000-a-week five-year contract in February 2016, is still expected to be fined by West Ham, although there is a growing recognition Bilic could be better served with the funds generated from a sale rather than keeping an unhappy player at the club.

Andy Carroll believes the performance against Palace showed the unity of the squad without their star player.

“I think we have answered a few of the critics, 100%,” he said. “With everything that has been going on during the week and everyone talking it’s been tough, especially as the lads are close to one another. To put all that behind us and work as a team has been fantastic. The fans were like the 12th man and were great with their support.

“It was a great day all round. All the lads were fantastic and professional. They know what it means to the fans and the club. We stuck together and everyone is hungry and dedicated – and it showed in the performance.”

Simone Zaza has cut short his loan spell at West Ham to join Valencia for the rest of the season. The Italy international joined on loan from Juventus in the summer, but never found his feet in London, failing to score in 11 appearances in all competitions.

With the terms of his loan dictating that the switch would become permanent if he made 14 appearances, he fell out of favour and the deal has now been cancelled, freeing him to join Valencia.