Charged after cancellation of free week

I've been charged three times (without me knowing it) after I cancelled a subscription that started with a free week. I've done everything correctly as cancellation guidelines stated, so there should be absolutely no reason for this to happen. Now that I found it out, I've cancelled it again only to get a message that I would pay half of a yearly amount, that message obviously disappeared and was not mentioned in any mail. Customer service do not answer (no surprise there, it's about cancellation), so I came here, probably to get no respond or some vague ones.

If this issue would happen when I forgot to cancel, that would be on me. That is why I demand to get a refund on the last transaction, stop the billing (because I don't trust your systems) and stop the cancellation payment. This was not the introduction to your company I wanted to get.