Changing my contract problems

My current contract was ending and prices were rising so I phoned Virgin to try to get a better deal.  After some discussions I was sent pre-contract documents which I was told were valid for a week and that someone would contact me in a couple of days.  This didn't happen so seven days after receiving the documents I phoned Virgin and the person who took my call said he couldn't get me the deal offered in the documents so transferred me to another person who after trying for some time said he couldn't get me the deal either.  I'd been on the phone for nearly an hour so he said he'd contact another person and I'd receive a call back in a couple of days.  This didn't happen.  So now I'm a week off the end of my contract and I can't find anyone in Virgin who will get me the deal offered in the pre-contract documents.  As I can't afford to pay the increased rates that will start next week I'm left with no alternative than to seek another provider with all the rigmarole that will entail - unless some kind person on this forum can advise me on how to get Virgin to respond.