Vox Telecom Tech and Accounts service is non-existent

I requested Vox to change my package to a different one in May this year. During this time a total of 0ver 50 emails and telephone calls went back and forward between us, due to total lack of service and a total lack of interest on Vox's part. The changeover finally happened on the 21st August. I now receive the account from them, for the new month at the new rate, plus a pro rata value from the 21st to the end of August. However I have not received a *Credit Note* for the same period from the 21st of August to end August for the balance due to me on the old package, which had already been paid in full earlier in the month. Come on Vox! When will you ever get it together!