Britney Spears has left

rehab after a month-long stint - a 29-day improvement over her previous personal best, sure, but shy of the typical 45-day stay at her facility of choice. "[Britney] has been released by the Promises Malibu Treatment Center after successfully completing their program," her manager tells

People in a statement. He has also asked that the press now respect her privacy. Spears voluntarily entered Promises - which tags you $48,000 for a month's stay - on Feb. 20, after a weekend romp capped by her shaving of her own purty melon. UPDATE: A source close to Kevin Federline tells TV's Extra that Brit's estranged husband and his attorney "are not about to return the kids [Sean Preston and Jayden James] as a reward for completing rehab. Kevin has had full custody for six weeks prior to her rehab... and will continue to have custody. [Spears] will have increased custody as long as she demonstrates she's living life with the best interests of her children."