Note: you're not contacting eBay by posting on these boards. They are public forums on which any eBay member can post, and the responders are, like you, fellow eBay members who give voluntary helpful advice and information. (The standard of help is usually well above the type of cut-and-paste help provided by eBay customer service.)
I'm not quite sure why you are blaming eBay for your having multiple eBay accounts and having used a different eBay account for purchasing something. I don't mean to be rude in suggesting that that is solely your responsibility. Why do you not check your emails and see to which email account the transaction details were sent? That should help you to isolate which eBay account was used.
You can (normally) try contacting eBay by using the Have us call you facility, but do you expect the CS rep who will contact you to tell you which eBay account you used? Is that not a little like contacting your car manufacturer to ask which key will open your car door, when hanging on the rack right in front of you is a row of car keys and fobs?
Well... if you seriously cannot work out which account you used, and you do want eBay's help, yes, there are humans employed by eBay to help with Customer Service questions. (You should not put your email address on these boards. These are public boards, available for all the world to view. Please be wary of spam email to your email address that arrive as a result of your having posted the email address here. I will ask one of the forum moderators to remove your email from your post, for your own privacy and protection.)
eBay's "Have us call you" option is by far the best way to get in touch with eBay. However, there's a notice at the bottom of the page at the moment, as follows:
To do what's right for the health and safety of our employees, phone support is not available right now. We recommend that you search our help pages for the information you need.
If you need further assistance, you can select one of the contact options below. We're working to restore our normal service as quickly as possible. Take care and stay safe.
I'm sure you can understand that eBay are probably sorting out issues with regard to social distancing and other safety issues in the workplace for their customer service representatives, resulting from the COVID-19 pandemic. In the meantime, the chat facility is probably your best bet.
Good luck.
