Help with escalating complaint in dell uk

I paid £150 for my laptop to be repaired in Dec 2012. Shortly after receiving it back I noticed there was a problem with the battery charging port. I want this problem repaired as was promised when I sent it for repair or my money back. I've been trying to find help since Jan 13 but am told I'm lying and there's nothing wrong with my laptop or that I need to pay for further repairs. I spent over £100 on calling Dell at the start and asking for help, but was repeatedly put on hold for no apparent reason and had to stop calling when I realised one call cost me over £70! I have been trying to escalate a complaint above the Dell customer care team but am told that Ramjee and Raksheeth at Dell in India are the absolute highest Dell employees that hear complaints, they tell me their position is final, which I won't accept. I asked for an address in the UK to raise a formal complaint, eventually they gave me an address in Reading. I wrote a letter and received an email response from the same unhelpful people at Dell in India. I have bought a replacement battery and charger as Dell customer care said it was this that was the problem, but even with brand new genuine dell replacement products the problem remains. I am so tired of this, it makes me cry every time I try to use my laptop and I want to kill myself. I will die before I let this lie as Dell have over £300 of my money and I still have a broken laptop. Please please please can someone help me?