The tour operator and its agents act only as agents for passengers in all matters pertaining to transportation, accommodations or other services not provided by ETICA-Metropolitan Touring. As agents, all tickets, exchange orders or vouchers issued by them subject to any and all terms and conditions under which such means of transportation, accommodations or other services are offered or provided. The booking agent, airlines involved and general agent will not be liable for any vehicle furnished by any such other party, firm or corporation in carrying out or falling to carry out arrangements previously agreed upon, not for the negligent misconduct of any such other party, firm or corporation in providing or falling to provide, are not to be held responsible or any act, omission or event during the time passengers are not on board their conveyance. The passenger contract in use by the airlines concerned, when issued, shall constitute the sole contract between booking agent, airline general agent and the purchaser of these and/or passengers.