Deducting unauthorised debit orders 2 months after cancellation

So I cancelled my contract with rain end of March, they came to collect my router on 6 April, as from my cancellation date the router was unplugged. I received a confirmation of cancellation on 26 April. There was no invoice for April, there was no invoice for May. April went by with no issues, come May, they took 3 debit orders from my account WITH NO PRIOR NOTICE, there is no invoice for April or May. I sent rain an email asking why they deducted money, no response. Im afraid to have money in my credit card as I do not trust rain not to deduct money again. I went to the bank to dispute these payments and to reverse them, but they can not and they will be charging me for this. I work on a very strict budget and this has got me deep into the red this month. Guessing if you are a big company you do not care about the peoples money you take with no authorisation or the way that it negatively affects them. Ive got screenshots of proof of cancellation and that I do not have any invoices outstanding with them. This feels ******** to me.