7 years, 100,000 miles is an option. I don't know how much extra the option is as I have a 7 year 200,000km (120,000 mile) extended warranty (BMW Canada) and mine was close to $4K. So the contract you signed is for a legitamate product (I think it would be different if BMW NA didn't offer a 7 year/ 100,000 mile warranty) and therefore couldn't be deemed void from that perspective. The next question I would have is what is the difference in cost between the 70k and 100k policies? We may only talking about a couple of hundred dollars or we may be talking about a thousand, or more. If it is in low hundreds I'd hold them to it as a cost of rudeness. If it is over $1k I'd do as dunderhi suggests.
2011 535i xDrive, Dark Graphite Metallic, Veneto Beige Dakota Leather, M Sport Package, 316, 322, 3AG, 5AD, 5AG, 5DL, 609, 620, 655, 677, 6FL delivered Christmas Eve '10, Mods - quad tips, 20% tint, JB4.