Blue label complain.

They sold me a phone A55 in August 2022 online, which I agreed on thinking it's the right phone. They delivered the phone but it started by not charging, and when i put it in the charger it consume the battery instead of filing it up, it suddenly stopped working in March 2023 until today and I called them to report my problem they promised to log a call for the courier to come fetch the phone to fix it because I have been paying their instalment every month, when I try to make a follow-up They keep on saying they will send the courier guy. My issue is that I'm paying for something that I'm not using. And when I stop paying for their services they threatened to blacklist me, and not even looking at the issue and resolve it