Postage charge £6 but actually £4 on packaging

[nicolab3465]

I am not sure what the correct way of dealing with this is.  I have contacted the seller suggesting there has been a mistake with the postage charge and have had no reply.  Even allowing 50p for the new padded envelope saying the postage cost was £6 and the costs only being a max of £4.50 is dishonest.  I thought eBay was quite strict on this sort of thing but if the seller does not reply what should I do?  I have not sold things myself and am only just begun to do so which is why I have now looked at the Royal Mail website which says "Royal Mail Signed for 2nd Class £4.00".  I look forward to receiving any advice anyone can give me about this.  

[plpmr]

The seller quoted a price to get the item to you and you agreed by buying but you label the seller as dishonest and your calculations don't even take eBay & PayPal fees into consideration.

The very best advice is to look at all the facts before accusing others.

You say - “I have not sold things myself and am only just begun to do so “

But your feedback shows you started selling over a year ago.