If that was me, id call and speak to a supervisor and let them know youre going to make a complaint to the ACCC and obtain legal advice if they dont reinstate your account. When you do that, make a point of asking the persons name, and ask if Ebay records phone calls - request that they do as soon as you get onto a supervisor.
Being prejudice toward you because of something your sister did (or anyone else in this world) is not an ethical business practice. Legally, you do not have to prove you are two different people - they are the ones accusing, therefore the onus is on them. and when you speak to them - use those words.
Households are not condemned because of what one person within might have done, or because two people MIGHT be the same person.
Can you imagine if someone like Telstra cut your account because they thought you MIGHT be your sister or someone else, and they had done something wrong? or woolies? "oh you cant come in here anymore because you might have something to do with someone who behaved poorly here. "
Not in this lifetime. Ebay is no different. Offer them relevant ID to prove that you are not your sister. thats all you need to do - whether or not their business systems allow this to show the difference between the two people is not your problem.
