Troubled pop star Britney Spears reportedly believes she doesn't need treatment for drug or alcohol abuse because she is suffering from postpartum depression. The TOXIC singer has been in rehab in Malibu, California for two weeks and is furious with friends and family for making her seek counselling. A source tells American publication Us Weekly, "She's convinced she's suffering from postpartum depression and does not think she has an alcohol or drug problem. "She's angry at her family and her manager for pressuring her to enter the programme. She feels she was ambushed." Spears checked in to Promises Residential Treatment Centre on 21 February (07), after several months of hard-partying. A source says doctors are still concerned about her condition saying, "They're in shock at what bad shape she's in." The 25-year-old has reportedly not been on her best behaviour at the facility. A source adds, "(She) has been getting in tons of trouble. (She's) been reprimanded for making cell phone calls, has left the facility to shop, and now she wants to leave rehab for good."