Why debit an expired contract where a service is not rendered

This company really is way backward and terrible, it makes sense they have been operating for so long but still cannot take a lead in the industry. App**** for a Fiber Router last year, it took more than 9 months to get my money back because it was not installed, but they kept debit my account.

Now they continue debiting my account while the contract has ended, when you take on their product they says on expiry date contract get cancelled, so how can they continue debit my account, i reverse it with my bank and they just keep coming back.