Double debits 3 consecutive months

I have had Cell C fibre for 6 years, I had a contract for 2 years then I moved and took up a new contract upon moving which I had for 4 years until end of April this year and renewed my contract with a better package effective 1st may this year. Cell c recently migrated to a new system which caused double debits with two separate debits end of March for my my march debit. I have NEVER missed a payment in my 6 years with Cell C so I was understandably upset the first time, I waited 3 weeks for them to reimburse me plus they credited me for debits penalties that rejected to other services because of them overcharging me. I was assured it would not happen again, yet end of April the same thing happened and now I was livid and again I waited almost 3 weeks for the reimbur*****t. I upgraded my contract effective 1st May which I had been planning to do and I thought well it's a contract on their new system so there shouldn't be any finance issues I hope and it only activated the 1st per my instruction, they also discounted my new contract which I was appreciated given the stress they put me through. I was sorely disappointed and extremely livid, I was beyond angry when once again they debited me two premiums this time in one debit end of May, 3 months in a row Cell C *****ed up, I cannot understand how Cell C can not get their system or employees up to standard and make the same mistake 3 months in a row. I have spoken with team leaders and it's a endless battle to speak to anyone with high authority nor can I get a direct contact number and email, I have wasted my TIME, MY Money and MY energy chasing cell c every month to Reimburse money that was essentially ****** from me with is given ZERO priority when this NOT in anyway my fault and all falls onto Cell C when I have never failed cell C. I so much wanted to change service providers but I work from home so I cannot afford any down time with a switch on service providers so I upgraded with them despite my misgivings and it was the worst decision. Why must I chase them to Fix their error, I don't want Apologies. I want it fixed and paid back to me so that it NEVER happens again. It should be reimbursed within 48 hours, NOT 3 weeks, we are now a week since their 3rd F up and still no refund.