Get a garage to check them. If they do need replacing, consult your finance company about the cost of replacing. If they don't budge, take it to a local trusted mechanic. As long as the garage uses OEM parts then it won't affect your warranty. Getting any type of work done at a dealers is extremely expensive. Not only do they ask you to pay the price for the car, they want to charge you the earth for just maintaining it. If the car is still under warranty though, focus on getting the parts replaced under warranty. It's rather the dealers are trying to con you or the parts aren't fit for purpose.