Personally i think you were mad to buy a car that was advertised for a LONG time as a 00 and drive it home on 99 plates. You say the documents are for 00 altezza, then why did you not change the plates?
Japcars are well known for putting on any old plates and log books from what ive heard. But at the end of the day, you signed the dotted line for a 00 altezza and knowingly drove it on 99 plates. What do the plates belong to did they say?