No response to crediting overcharged voyager miles

1. Redeemed Voyager miles on 26 Mar 2015 for flight awards. <br> 2. Emailed Voyager on 30 Mar requesting that they credit account with overcharged 19000 voyager miles.<br> 3. Reply received with ref SR*** on 30 Mar, offering to reverse flight awards at a cost.<br> 4. I rep**** on 30 Mar that I did not want to reverse the awards, but wanted the overcharged miles credited to my account.<br> 5. On 19 Apr I sent a reminder for a response and again on 7 May.<br> 6. On 11 Jun I phoned the service centre to try to resolve the problem. Was informed by agent that the matter needed discussion with a supervisor. The call was cut off before I could leave my number to receive feedback.<br> 7. Sent an email on 11 Jun including my contact details.<br> 8. Sent a further request on 24 Jun for a resolution, but no acknowledgement even of receiving my email. <br> <br> Your help would be appreciated in getting Voyager to reverse to overcharged miles and credit my account.