Horrible service from telkom mobile regarding my bill

I have a contract (account number ********** 28) with Telkom mobile where I have a Samsung S8 and a data only sim with the latter being cancelled last week. I upgraded to he Samsung handset in December 2017. My monthly installment is R628 however end of May I was charged R1100.

I called the customer service (case no: ********** 6) immediately and was informed I| had been charged pro-rata yet again in April which doesn't make sense as I was charged pro-rata end of Jan for the upgrade done in Dec. I was told case was going to go into investigation with a guaranteed response in 72hours which didn't happen. When response finally came I was told the same thing the consultant had told me. Can Telkom just answer:

1. Why am I being charged pro-rata yet again for the same device upgraded in December and I have not taken any new contract since.

2. What exactly did the investigator investigate for them to come give me the same feedback given by consultant?

3. When will my money be reimbursed?

2.