No coverage but Rain wants to charge me.

No coverage, got my 4G SIM on 28 Jun 2022, Rain coverage map says I'm in a coverage area but there's no signal on my phone. Tested the SIM by driving 10KM away from my residence and it worked. I asked for the service to be cancelled on 29 Jun 2022 but Rain wants to charge me for the whole month even though I live in an area with no coverage. I only ordered their 4G SIM because their coverage MAP says I've covered for 4G.