I realize this is unsolicited advice, but I thought there was a chance it would be helpful to you:

Stop sharing an ebay account with your mother. Tighten your boundaries in this relationship until they work for you, until you have the contact (or not) as you want. Eliminate interactions or events or topics of conversation that you don't want to deal with. Consider whether you should break ties with her completely, at least temporarily.

I think if you take action to change your relationship with her, rather than continuing to put yourself in a position where she can engage you through these kinds of passive aggressive techniques, you will no longer be in situations where you "want" something from her.