How to deal with a potential scammer, advice please?

It had to happen to me eventually lol. I've just sold anew mobile phone on ebay and I thought I'd done everything right to try and prevent scammers. I've got photos of the IMEI No. and stated I had it in the listing, put detailed photos on the listing, sent special delivery etc - but lo and behold today I get an email from the buyer -

their is a fault on the mobile phone ive been to the orange shop and they say its faulty do you have another one or a refund.mike.

:mad::mad:

The phone was brand new and sealed, I'd never installed the battery or turned it on (I realise now I should have and got a photo, but hindsight is a wonderful thing), so there is perhaps a very slight chance they're telling the truth, but to be honest with their low feedback and 2 lines on an unspecified 'fault' I don't really believe them.

I'm planning on replying something along the lines of -

Hello, I am very sorry to hear that. As per the listing, the phone was brand new and I sold it in good faith, having never installed the battery myself or removed any of the packaging as you will have been able to see. Could you perhaps provide details of the fault and documentation from the Orange shop to confirm that there is a problem? In that case I would agree for you to send it back to me for a refund. Please bear in mind that I have detailed photographs of the phone and of the imei number so I will be able to confirm that it is indeed my phone when returned, and whether it has sustained any damage.

Do you think that's ok? Anything else I should put? I'm not sure about using the Orange shop documentation bit, I don't expect them to get anything, but I'm obviously not handing their money back just like that on the basis of a spurious unspecified fault.

Thanks in advance for your experience