Charged incorrectly twice

I recently cancelled my fibre order with afrihost due to the dismal service experienced by everyone involved. Upon cancelling the order i was sent an invoice for the "free" router i was given for my order. After querying this with the accounts department i was told that if I return the router, the invoice would be cancelled. I was instructed to request a collection by the accounts department so the process could be arranged. a courier collected the router on Tuesday morning and i believed everything would have been closed. when i woke up on Wednesday morning i was notified that my account was debited for the router which was returned. I of course queried this with the accounts department to no response. i woke up this morning with another notification that my account was debited again by afrihost for a delivery charge which i found strange due to the reason that i collected the router from their offices. I have been a client of Afrihost's for almost 5 years and this has been an absolutely atrocious experience.