Unauthorised debit orders. Theft from my account!!

Unauthorised debit orders from my account, adding items to invoices after the invoice has been paid (including proof Emails from Accelerit confirming paid invoice). Fibre connection also not great with my speeds constantly sitting betweem 5Mbs and 15Mbs on a 20/20 line. Have to restart the router a couple of times a day. Avoid this company!!