Mtn ***** of upgrading my contact

I Have a cell phone contact with Mtn , which It was for R199.00 and now they are charging me R500 and which I did ask them to change the package . I have logged the call with them and they have requested that I go do the affidavit which I did and send it to them with the copy of my ID copies. Since January 2018 they are still failing to resolve my case now they are sending me letters of demand because I have to reverse debit order because I cannot manage to pay R500 because I didn't request that .

see the respond from MTN

On Fri, Apr 20, 2018 at 4:58 PM, ***** ********** wrote: Dear Valued Customer, Thank you for your email. Your query will be investigated and you will receive feedback within 3 business days. Your reference number is ( ********** 9 )/Re: 1- ********** 3774 and is also displayed in the subject line of this email. Please do not remove the reference number from the subject line of the email as it enables us to track your query. Kind regards, Customer Relations *****

after a month I received the following email again which they are saying they cannot pick up my reference number which they have gave me and I have to send them the copy of my id again which Is a delaying tactics and affecting my credit record

Email from Mtn ***** via mtncloud.onmicrosoft.com Jun 7, 2018, 8:13 PM

Good day Thank you for your email. Kindly note, I cannot pick the ticket. Kindly provide us with ac oopy ID stamp by the police. Warm regards