I've just had my first experience of this 'simple delivery' and I am not happy!

I have a large number of items on Ebay for £5 each and they sit there and occasionally one will sell. It's really only a bit of fun to sell some items my mum made to keep her busy. Well an item just sold and not only did the notice it had sold not come through until 5 days later, I post the item and then go to mark it as posted, as I always have, and I'm very confused as I can't do that and it's telling me I have to use Ebay labels and posting.

Well I knew nothing about this change and when I checked, all of my items were automatically changed to this simple delivery. What's worse is that I have been charged £2.74 out of the selling price, am told it's tough and I can't reclaim it and the item is still marked as awaiting delivery!

The buyer received their item a week ago and it's still marked as not delivered. What do I do? 

I have now gone through all of my listings and changed them all to custom delivery. I am concerned this will change again without my knowledge and I will lose out again. 

Any advice??