I have had car insurance from Direct Line, on and off, for a couple of years now. I would never use them again.
They're not competitive on price and the customer service is appaling. The operatives in the complaints department have no grasp of company procedure and are frequently rude.
The worst of the consistent failings was not cancelling my policy when requested and charging me for three extra months. They then pursued me for this money through a debt collection agency when actually they still owe me the balance of my premium.
They continue to bombard me with advertising despite my request to be removed from their mailing list. They are cheapish but it's not worth the hassle and, anyway, there is cheaper and better.
Steer clear(no pun intended!).