Source: Bang Showbiz News'Baby' hitmaker Justin Bieber has reportedly been calling his former girlfriend Selena Gomez up to 100 times a day. The on/off couple recently called time on their relationship and Justin, 18, is reportedly so upset he has been ringing the 20-year-old actress constantly and begging her to take him back.A source told HollywoodLife.com: "Justin's devastated and pathetic right now. He's calling her 100 times a day and she's not picking up.""[Selena and Justin] flew to Mexico for New Year's Eve (31.12.12), but had a blow-out argument on December 30 and broke up. Selena left Mexico that same day and Justin left for Los Angeles on December 31 They haven't seen each other since."Friends are unsure if the pair will manage to work out their differences this time.A pal recently said: "Justin and Selena were together for a long time. They love each other and will always care about each other, but it just isn't working between them."This might really be it for the two of them. They're over going back and forth and all the fighting and reconciling. They're finally coming to understand that no matter how much they try to make it work it won't right now."