https://www.ebay.com.au/help/buying/buying-ebay-plus/buying-ebay-plus?id=4755

I’m quoting from the above Help page.

❝You can pay by credit or debit card, or by PayPal. We'll charge your membership fee when you sign up, or on the first day after your free 30-day trial period (if applicable). After that, your membership is renewed automatically each month or each year, depending on your plan.

If you want to change or cancel your membership, make sure you do so before your next payment date to avoid being charged when your plan renews. You'll still receive eBay Plus benefits for the remainder of your membership period.❞

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Did you not read the terms & conditions before clicking onto the free trial button?

You’ll have to cancel your subscription yourself. Quoting:

❝Cancel your eBay Plus membership

You can cancel your eBay Plus membership at any time. Here's how:

1. Go to your eBay Plus membership page.
2. Select Edit membership.
3. Select Cancel membership.

If you change your mind and want to sign up again, you'll just need to choose your preferred membership plan and provide a payment method.

Fee refunds and eBay Plus benefits when you cancel your membership

• If you cancel during your free trial period:You won't be charged any membership fees. You'll still receive all eBay Plus benefits until 30 days after you signed up for the eBay Plus trial.
• If you cancel after paying the membership fee: You won't be charged on your next renewal date. You'll still receive all eBay Plus benefits until the renewal date.❞

You may still be able to get back the subscription fee, but only if you contact eBay within 14 days of the payment. See below:

❝Tip

If you forgot to cancel your annual eBay Plus membership before the fee was charged, you can contact us within 14 days of your payment date to cancel your membership and receive a refund. This only applies to annual memberships that were renewed automatically after a free trial or at the end of a membership term, and your eBay Plus benefits will end when we process your request.❞

Other members are not going to pay your fees for you

It is your responsibility  to read the terms you agreed to when you signed up for the free trial, and it was your choice to sign up and not use it 

Your responsibility to also know when you needed to cancel by in order not to be charged to the fees you agreed to

Only you can cancel, and you need to do so before the next lot of fees will be due