Cancelation problems

On the 4th of August I send all required documentation to cancel one of the services I had. Couple of days later, I've received the call that the service will be cancelled on the 31st of August as requested. On the 2nd of September I called to check if it's done, just to find out that is not. After that I've follow up numerous times, but issue is still not resolved. How difficult is to cancel the service?

I need someone to please contact me and help me to solve this issue, please. My reference number is: ********** 7