Query of invoice amount

[purple_fraggle]

I'm being charged £35 in this months invoice. I have been charged insertion fees (from what I can see) for all my listings.
I set them on the app and for all my listings I was told the fees were £0.00 before I listed them. I made sure of it as I was listing a lot of items for a clear out. I have no evidence of this as it was on the app and I don't know how to prove what I was told.

Edit - when you list an item on the app, before you approve it gives you a rundown of the fees of listing the item (buy it now etc). Everytime, these were listed as Free when I accepted them. I am now being told they weren't. 

What can I do? I have had bad experiences recently with ebay customer service for sellers so I feel stuck.

Thanks in advance
Rowan