i have one open case i can not access resolution centre

[Muscletricks]

i can not access response on an open case i have sent customer a receipt to prove proof of posting but can't update this as my response 

[kernowlass]

@Muscletricks 

To win a dispute for non receipt you would need to add a tracking number that proves delivery of the item to the buyer.

Proof of postage just proves you posted it, it does not show that the buyer received it.