The above responses cover the issue properly. If at ANY point, the car was tuned, then you have a problem. WEIRDLY though, this is something that is checked when the car MP is transferred from the seller to you with the BMW 1 million point check. oddly it doesn't seem this was identified when buying, but now after owning and driving for a year. IF the tuning flag is dated before your car was sold to you and MP transferred, then actually this isn't your problem as the Mp check/inspection should have identified this, so thats the argument to use to fight it. If the tuning flag is dated after you took ownership and had the car inspected at BMW to transfer the MP, then you have some explaining to do.
if you think they will not void MP, you would be wrong, guys have had MP voided for spacers as mentioned above, steering wheels, non approved exhaust tips, non approved led light bulbs and i have even heard of MP voided on cars because of coding non-factory options on the cars which created faults in the electrical system which threw errors when plugged in for an oil change.
Get the dealer on your side to help.