Rome, April 16 - Consumer group Codacons on Tuesday turned once again to Italy's top administrative court in an attempt to block privately-sponsored restoration works on the country's world-famous monument the Colosseum. Codacons has an on going legal complaint against the 25-million-euro renovation plan by shoe giant Tod's, claiming that the bidding process lacked transparency and yielded too many concessions to the company owned by Diego Della Valle. The consumer group asked the court to provide previously deposited acts on sponsorship rights for verification. Codacons is also asking that the exclusive sponsorship contract be cancelled and new legal proceedings be opened, claiming that advertising rights were increased ten-fold over the original agreement. The regional administrative court ruled against Codacons' complaint last summer, but Codacons filed an appeal, which was also overturned in February. Restoration work on one of Rome's most important historical landmarks is set to begin on May 20.