Harley Davidson

2018 fxbrs breakout purchased brand new from the dealer and I've been more than happy with my bike until recently when I noticed my electronic fuel gauge would not read full, took the bike back to the dealer and was then told it was due to my screaming eagle tuner stage 1 and was told that it was not covered under warranty. I don't think this is fair as everything was purchased all in one go and if the tuner is the problem I should get a refund on the tuner that was sold to me by the dealer and another tuner used as I did pay for a stage 1 on my new bike. I love my Breakout but please, please, please someone help me with this issue as my new bike warranty ends 21/3/20. I have worked very hard for many years to be able to buy my dream bike and I'm far from being well off to be able to lay out large amounts of money to have this issue fixed. I'm in dire need of some help and believe harley davidson being the reputable company it is known for will come through for me as a loyal customer.
I thank you in advance and await for your outcome.