An identical twin whose sister was murdered by her stalker ex-boyfriend has revealed she wishes she had done more to save her. Grieving Nikki Thomas, from South Wales, says she wants to turn back the clock and tell Jenna that she didn't have to 'put up' with her former partner's obsessive behaviour, including bombarding her with hundreds of calls and texts a day. But Jenna, who was strangled to death by Philip Packer in a jealous rage in 2008, never reported his behaviour to police - and paid the ultimate price. Scroll down for video . Nikki Thomas appeared on This Morning to tell how her sister was murdered by her obsessive ex . Now Nikki, 27, is warning others to learn from her sister's tragic story and not tolerate stalking behaviour. As part of Stalking Awareness Week, Nikki, from North Cornelly, ­appeared on today's This Morning in honour of her sister. She told presenters Phillip Schofield and Amanda Holden how Jenna had started a relationship with Packer, who was 28 years older than she was, when she was a teenager. But shop worker Jenna found Parker, a nightclub doorman, could be obsessive and controlling so she eventually ended their relationship. However, Nikki said he then wouldn't leave her sister - then aged 21 - alone. She recalled: 'In 2009 she left him saying she wasn't happy. He was very controlling, obsessive and jealous. 'He wouldn't stop contacting her. He would ring 300-400 times a day and that was just phone calls. There were also texts and visits.' Jenna was strangled to death by Philip Packer, pictured, who used to hound her with calls and messages . Nikki said neither she or Jenna realised how far Packer would go and 'kind' Jenna didn't consider reporting him to the police. Nikki said: 'My family and I were worried but she thought she had a handle on it. She never said she was frightened for her safety. 'She wasn't scared of him but it was unwanted attention - she made that clear to him but he persisted. She didn't go to police as she thought she could deal with it.' Nikki said Packer would often turn up unannounced at Jenna's house to drive her to work, or if she was waiting at the bus stop, he could pull over and offer her a lift. This is what happened on June 24, 2009, but Jenna never made it to her work place. After offering her a lift, Packer, then aged 49, took her to a layby and strangled her to death. He then drove to a police station and told them he had a dead body in his car. Six months later he appeared at Cardiff Crown Court where a jury found him guilty of murder. Nikki and TV presenter Rav Wilding, left, appeared on This Morning to promote Stalking Awareness Week . He was jailed for a minimum of 18 years (later reduced to 16 years). Nikki now wishes she had urged her sister to put a stop to Packer's stalking behaviour. She could have sought a restraining order preventing him from contacting or going near her. Nikki said: 'If we could turn back the clock I'd tell her you don't have to put up with this.' She is hoping others will heed her warning as figures from the National Stalking Advocacy reveal that one in six women and one in 12 men are stalked at some point in their lives. TV presenter Rav Wilding is also supporting the campaign after being the victim of a stalker himself. He revealed on This Morning how a woman used to bombard him with hundreds of 'vile and grotesque' messages. Rav had to take out a restraining order on a woman who was harassing him . He said: 'She was eventually convicted for harassment  and now I have a restraining order - that's all I wanted. Now she can't contact me directly or indirectly.' Rav added that if people are concerned about harassment, they shouldn't think they are being silly and should rest assured the police will take them seriously. 'You don't have to put up with it,' he said. 'If you are getting unwanted attention you can go to the police and get action.'
Jenna Thomas, 21, was murdered by ex boyfriend Philip Packer.
He hounded her with calls, texts and visits after they split up.
Then strangled her to death one day in jealous rage.
Her twin, Nikki, now wishes they'd taken stalking behaviour more seriously.
Urges others not to 'put up with' harassment.