It depends... on electronic ticket, they are serial numbers. You will get two consecutive numbers on a reservation for two passengers.

On generic paper stock that travel agent use, it is actually pre-printed. They only add three more number at the beginning to distinguish the airlines... this obviously is a dumb idea. Once a number is used by an airline that number can not be used again by another one even the numbers will be different at from the begining three digits.

There must be a way to trace the origin of that ticket issuer since IATA (maybe?) keeps track of which agency get ticket printed that range of number.

It's like you can find out which province and office your Soical Insurance Number is issued based on the first three digits.

The question / problem is.. they probably will just ignore you. They are not answering your calls already. The only way to get their attention, unfortunately, is probably with a law suit.