<human>: I'm 25, sister is 34

Two years ago my sister used my security code to get a phone on my vodefone account and change the address to hers. I was angry at the time and threatened legal action but she later told me that she had sorted it out and it wouldn't be on my name. It would be on her credit report etc.

3 months ago she when into debt on the phone and can't pay it back. She assured me that it wasn't going to affect my credit.

 Last week I checked my credit report and found that it's still on my name with the new address. It's now overdue too so its pulling down my credit score.
Since then I've opened a report with ActionFraud, the phone company and my credit reporter. My credit reported sent me a letter saying that the phone company wouldn't let them remove it from my report, and I've heard nothing back from the phone company of ActionFraud.

I've now offered my sister a get out of jail free card. If she pays half now, I'll pay the other half and she can pay me back monthly.

What should I do if she dosent take this offer, if she "can't afford" it...?

I can't afford to pay the £300 outstanding right now - I'm going to Chicago for Christmas from the UK to see my fiancee. 

I need my credit to be clean so my fiancée and I can get a loan for her visa and for a marriage next year... Should I pursue a fraud charge? Will this have a major effect on my credit? It's affecting my health I'm so worried about it... Can't sleep, I can feel my heart race at night thinking about it... I need to get this fixed one way or another. Her relationship with me dosent matter. Honestly I don't care about her anymore but would rather a quick straightforward resolution than getting police involved and whatever.  Any advice would be appreciated.

Summarize the given text in a few sentences.
<bot>: sister opened phone account in my name. Is now in debt. Offered her a way out but if she dosent take it, should I pursue fraud report?