Iphone 12 Pro slow charging

I bought iphone 12 Pro in Jan and within first 10 days, i raised the same issue of very slow charging on Magsafe charger with customer support and since then i have been visiting apple store but of no use. Phone takes much longer time to charge and when i asked for phone replacement, they are refusing to replace even i had raised the issue in the first 10 days only. Lot of time being wasted without any proper support. This is the prize apple is paying to its loyal customers.

How to get the phone replaced..?