"the phone number in my account is a land line"

Is there a mobile number you could use ?

 There's a drop down box option in  your contact info  to change from  phone type:  landline to mobile.

Then click "save" .

Oddly enough for an account  with a landline  requiring  verification,  a message  shows:

"If verification is required, you agree to receive a pre-recorded call to this number"

so probably inexperienced  eBay agents is the reason this hasn't been mentioned  to you.