Are you sure that this restriction is "indefinite" i.e. permanent on eBay? If so, you have a real problem. Hopefully if this was just a first purchase restriction it may not be permanent, but just some query over your payment method.
If it is really permanent, this means what it says and eBay almost never removes it.
The cause may be entirely beyond your control. For example, eBay may have associated your account with another account that has been restricted. This can happen if there's another eBay user at your address, or even if there's an electronic trail that connects you such as sharing the same connected device.
You can try contacting eBay customer support, but if it's really permanent don't build any hopes on it being lifted.