if memory serves the D1S has an ignitor integrated into the bulb, don't think its the same.

I had a bora that a retrofitted factory xenons to a few years ago and I had to order a ballast for it too. I found the best source was ebay germany.

The german word for ballast is steuergeraet, so model number + steuergeraet should see you sorted for the ballast. Try to get the bosch, or whoever the OEM is model number.

I found that the one for the bora was being used in a litany of other cars and ironically, the same part for a merc was way cheaper, go figure.