DISSATISFACTION WITH MTN

I have paid an incorrect amount into my MTN account on the 26/10/2018 of R2600 instead of R260. Request for a refund was sent on the 26/10/2018, proof of payment as well as banking details have been forwarded and to date NO REFUND. I have requested that a manager contact me on numerous occasions and no call back done. I have spent time on wasted phone calls and have been put on hold continuously.My last call was 35 minutes long where 29 minutes was spent on hold. My account was upgraded on a R299 data deal on the 27/11/2018, this generated an additional invoice of R591.14 on the same day . I WAS NOT INFORMED OF A DOUBLE BILLING and next billing should have been in December 2018 not November 2018. The contact center is extremely unhelpful and rude. I requested to cancel my upgrade and was informed by RONELL " you may do as you please, you are free to cancel " instead of trying to assist and resolve my query. MTN are a bunch of ******* and are trying hold back on refund due.