Thanks dx

Hi, I'll give you a quick introduction of what my situation is. In September 2011 I moved from home to a city to do a course in college when I was 17. I'm currently still living here and will be moving out sometime in June 2012. I also turned 18 in February (not sure if that has any relevance). Now I have a bill that of £1,300. When I moved in I was keen to pay bills etc (sharing the bill with 4 other tenants). The person who was currently responsible for paying the bill told me he wasn't paying it due to some rent problems and that he didn't agree for it to be put in his name. I was also 17 at the time so I wasn't able to set up direct debits to pay bills. I then told told the landlord can you help me sort the bills and also another tenant did the same (which was a 5th each of the entire bill). He rang up E-ON and said that we'd like to pay our share but not take responsibility for the entire bill. They said that's fine and they'll do the workings out etc then they rang me back and told me that I have to pay £100 and another bill for £600 I told them they've done it wrong and it needs to be divided by 5 not 2. A couple days later I got a bill in the post with the amounts she told me over the phone but it was a bill of £100 and a joint bill with my name on and the other persons name on which was £1200. I have since been having letters from debt collecting agencies and I'm terrified due to it may affect my credit rating and after next year I was planning on going to university this may stop me from getting a student loan to do so. E-ON say that i'm responsible to pay the entire bill and that it's my problem to find other tenants who are foreign and have moved back to China etc (which I have no way of contacting). There is no way I can possible find £1,300 to find this bill, i'm a student at college and my mum helps fund my accommodation through jugging two jobs which i'm so grateful for. Am I really responsible to pay the entire bill? and I'd be so thankful of any advice as at the moment i'm saddled with worry and this is constantly on my mind.