invoice from ebay

I rarely use ebay and only have been on there lately as my ads in gumtree have pop ups promoting to list for free in ebay which I have done and only because of that. I received today a very large invoice for these ads on ebay. I have not sold any of my items and now I'm expected to pay $120 for the service. I also not able to pay at the moment as my husband is not working and it is a lot of money to find considering I haven't sold any of my items. The second issue I have had is that an item was accidentally listed twice which I didn't realise, I wondered why I had a draft of the same item taht I had already listed and so I proceeded to finish the listing. I purposely wanted to sell my item at a price not by auction then I get a message from ebay followed up immediatley with a buyer text and paypal text saying my itemwas sold. I was completley taken offguard as I didn't know how it happened. This item to my knowledge was listed at a price and I have had buyers offering a price which I hadn't accepted as I wanted more money. than what they were offering. I have attempted to sell a slimline kitchen with one buyer buying then she turned around and said it didn't fit. i said that was fine and cancelled the invoice which I think is the right method going forward. I then separatley listed a fridge and then oven/cooktop combination thinking maybe I could sell these items as separate pieces but it seems I've created confusion in the market place. Today the buyer who cotntacted me last night was annoyed with ne as I said the item was not available just yet but that was only part of the reason, the other being it was way lower than the price I had previously been offered by other buyers overthe last 10 days approx. It was in fact $200 less. I didn't know until last night when that occurred that I had mistakenly listed the fridge by an auction method. I phoned the buyer and aplogised and he said he would be out of pocket for his insurance money of $30 for several days due to my error. I automatically retuend his money to his paypal the minute I saw and realised what had occurred last night. I am sorry for the error and I really hope that he can get his $30 back ASAP. I am still stuck with the $120 invoice from Ebay too. Can you help me to sort this out. Leanne.