Thanks sparklz.

I looked in the sales record and found there was a phone number in there.

Sorry! Should have looked there first. Silly me with egg on face! 

So I called the buyer and they gave me the street name over the phone.

I recommended that they log into their paypal account and correct the problem in there.

But they said we don't have a paypal account we paid by credit card.

I was a bit confused by that as we see a paypal record in the sales record and the same address error shows up in there.

It looks like a normal paypal instant payment to us.

So I'm unsure why she thinks she has no paypal account.

Anyway we can mail her item now. So problem solved.