This is nothing to worry about - no scam is going on, we would never add money on that you don't want to spend.
All that's happened is for one reason or another, you have added multiple items to your cart as well as the one you are trying to buy right now. This could have happened for several reasons - you may have got part way thru the ordering process then got a telephone call, or just exited the web page by mistake. When you then go back to our store and start the process again, your original order is still in the cart. Therefore subsequent ones will be added on top, hence the higher checkout total than you were expecting.
All you have to do is clear the items you do not want from your cart - simple! Each one has a little 'remove' icon underneath it, so just click those to remove the items you do not want or need.
If you want to start again completely, remove all the items, then hit the 'Home' button at the top and start over.
Either way this is nothing to worry about.