They grabbed 450 items of jewellery including diamonds and watches in a 2019 raid on the socialite’s London home.
Italians Jugoslav Jovanovic, 25, Alessandro Maltese, 45, and Alessandro Donati, 46, were jailed for a total of 28 years.
But freedom of information requests revealed paltry payments despite proceeds-of-crime orders of more than £435,000.
The Crown Prosecution Service said “prison sentences can be increased by the court” if the trio do not pay up.
Last year Tamara, 38, daughter of F1 tycoon Bernie Ecclestone, offered a £6million reward for the jewellery’s return.
Heiress Tamara said her family were still “traumatised” by the raid adding that only a single pair of earrings, a watch and a bag have been recovered.
She has vowed to “Mel Gibson style from the film Ransom” to get her treasured trinkets having waited in vain ” long enough” for police action.
In the 1996 thriller, a millionaire businessman decides to track down his son’s kidnappers by offering a bounty on the gang.
Tamara posted on Instagram that she would “happily put up 25 per cent of the value of anything that police are able to recover”.
She wrote: “If you are the source, you get the reward. It is that simple.
“With the total value of the burglary being £26 million – that’s a reward of up to £6 million for anyone that can help me get back what is rightfully mine.”
She also offered £250,000 to anyone who could “deliver Daniel Vukovic to the police in London”.
The alleged mastermind of the raid is believed to be hiding out in Belgrade where he remains free after the Met Police unsuccessfully applied to extradite him from Serbia.