Yep there are a lot of new customer only deals around which is annoying. We review everything either when it is time to renew, like insurances, or if we have signed up for any kind of deal and the tie-in period has ended. We save around £4-500 annually by doing this.
Its interesting that on the car insurance it didn't detect me as an existing customer when I signed up again, but it did give me the two car in one household policy for Mrs A having her car insured with the same people. This was two days before she cancelled because hers is now covered by the company.