Something could be going against u that u don't know about, for example the place u live in could be blacklisted. Request a credit report so u can check that everything is in order. I did that and found that they put one of my mother's loans on my report, because they had us linked to the same address. I wrote to them and told them to remove it. They also never had me on the electoral role for the address I currently live in, so I had to fill out a form for that. Go to
www.experian.co.uk and request a report, all u pay is £2. Someone told me that u can change ur savings account to a current account. It might be worth giving that a try, especially as the account has already been established, and a current account isn't much different to a savings account anyway.
Good luck, let us know how u get on