You may be eligible for a FREE replacement direct from Apple for some 2015 era MacBook Pros!
/Apple has determined that, in a limited number of older generation 15-inch MacBook Pro units, the battery may overheat and pose a fire safety risk. Affected units were sold primarily between September 2015 and February 2017 and product eligibility is determined by the product serial number./
Try typing in your serial number on this website: https://support.apple.com/15-inch-macbook-pro-battery-recall
Worth a shot?
Otherwise if you are willing to pay the Apple Tax, I am sure they will gladly take your money at the Apple Store for a new battery?
And as much as everyone seems to hate Apple, they are very much on-topic as they are the most popular *NIX based laptop ever created!
:P