Seller sent cheaper item & wont the difference hi

[flashponys]

Hi I desperately  need help/advice,

I purchased 2 CCTV cameras. received 1st one, then the seller decided to exchange 2nd one with a cheaper one.

1st off seller offered 10% refund, cos I'm as valued loyal customer.i have been arguing back & forward.seller then asked for my details so they could issue refund.

I've never been asked for my details before & it made me feel a bit uncomfortable so I tried to get Ebay to step in but felt like I was going round in circles & ending up back where I started.

Please can some1 point me in the right direction.

           Thank you 

               Flashponys 

[**peaseblossom**]

If you haven't done so already start a return on here:
https://www.ebay.co.uk/help/buying/returns-refunds/return-item-refund?id=4041
select "Doesn't match description".   The option to escalate it to eBay will appear after 3 complete working days. 

That has to be started within 30 days of delivery.   The seller will still have the option to refund without return but don't close the case until they do.

If it's past 30 days you will have to negotiate something with the seller.   It would be too late to involve ebay.