Rain behaving worse than a child whose "homework got eaten by the dog"

I have always been a strong supporter of Rain, however, I am now disgusted by their response to my direct complaint re double-charging. Rain promised me that when I signed up for a newer and more expensive uncapped data package, they would automatically cancel my then-current package. This month, I get a deducted for both home uncapped Rain packages. When I reach out directly to say that this doesn't make sense. They tell me that they will now cancel the previous package, but will not refund me for the overcharge, which was clearly Rain's mistake. Why would I need my slower Rain package and my new faster Rain package at home, both uncapped? They went on to say that there was usage on the previous package, as their excuse for not refunding, instead of owning up to not canceling the sim card. If Rain had canceled the previous package, the other devices that I do not use would have just stopped working, and if in need, I would have connected them to the new router. This was not a concern of mine, as Rain should have disconnected the previous sim, as we agreed. This completely unprofessionally poor and bordering on pathetic childish response from Rain is why I am reaching out on this platform.