Did you contact them through your eBay purchase? I have received a response the same day both times I've had queries.

In your My eBay Purchases section to the right of the item click on Contact Seller.

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@bigbrickshop wrote:

To access the flat-rate prices for eBay Postage Labels you need to use the eBay satchels (same as the old C&S satchels).

 

The eBay satchels can still be used on C&S until November. The new C&S flat-rate satchels are plain white and red.

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Sorry, I read it the other way around.  OK, so the new red and white ones are for C&S, and the few old C&S I have can be used for the eBay labels.  🙂 

Correctamundo   🙂