Usually things like battery swelling for such a relatively new phone is a safety issue caused by a manufacturing defect likely present when it was made and when you bought it, this is covered under Consumer Rights Act 2015, usually manufacturers will fix it without you having to push them. But regardless they're not doing you a favour out of the goodness of their heart, they know legally they are liable and have to repair or replace it.
Some companies/ retailers just need more prodding than others
Usually things like battery swelling for such a relatively new phone is a safety issue caused by a manufacturing defect likely present when it was made and when you bought it, this is covered under Consumer Rights Act 2015, usually manufacturers will fix it without you having to push them. But regardless they're not doing you a favour out of the goodness of their heart, they know legally they are liable and have to repair or replace it.
Some companies/ retailers just need more prodding than others