Vox Satellite service cancellation

Vox Ticket: VOX***2 I have tried to cancel my contract with Vox in March 2020 and after discussions with Vox sales agent I had to give a full month's notice which was done beginning of April 2020 to have my billing stopped end of April 2020. In theory I should not be billed from June 2020 onwards, but still get invoiced every month by Vox. It is now August 2020 and Vox still wants be to pay for the service until the cession is finalized to have the new owner accountable for the account.