I suggest that you might want to spend a couple of quid getting a credit report for yourself from one of the credit reference agencies (e.g. Experian). That will enable you to see the sort of data which is being assessed when the credit card companies look at your suitability for a card. If there is something there which needs correcting, you can then get it changed.
Not everyone has a landline these days but obviously that is one way that the credit people can check up that you are reliable at paying bills.