2008 Vauxhall Vectra Flickering Headlight and interior ligh

The headlights flicker on my Vauxhall Vectra whenever the steering wheel is turned. It affects the interior lights if switched on and is very conspicuous at nightime. According to Vauxhall, it's due to the electric pump associated with the power steering and its demand for power when the wheels are turned. They have now downgraded the problem to a "characteristic" from a "known concern" implying that they are not seeking a solution. I have since discovered that the problem is worse on some cars than on others but Vauxhall have no 'standardised test'. Thus, when I complained to Greenhous (a Vauxhall dealer) on the matter they made a subjective assessment - during the daytime. They simply looked at the headlights as I sat in the car and turned the steering wheel and then claimed that it was a "known concern". They were not prepared to do anything about it although they reported having fixed another Vectra on which the problem was more acute.

Does anyone else have this annoying problem with their Vauxhall Vectra or is it just me?