Is MTN a big company who doesn't care for its clients?

Sadly after being a loyal customer of MTN for many years - probably over 20 - I need to note the service received from MTN. Long story short, I took out a new contract with a new device which would mean I would have a new number. After some consideration I realised that this did not make sense as my number, which I have had for the time I have been with MTN, would change. On opening my account one month, I noticed that MTN had charged me the entire contract cost even though the device had been returned within the 10 day period offered to return it without being charged. This cost was around R3,000. I duly called MTN, explained the situation and was advised that this would be remedied within 21 days and the amount credited to me. What a surprise when I opened the following months account to see that this had not been credited to me. So once again I sit and wait on the phone to speak to someone about this. This sadly was not my only experience. At the beginning of the year I took out an additional Home Wi-Fi contract as I needed more data. On renewing my existing LTE data contract I once again realised that I no longer needed the Home Wi-Fi contract as the LTE data contract with its increased data on the renewed contract was sufficient data for me. So off I went once again to return the device. And you guessed it, 4 months later, I am still being charged for this device. It appears that once MTN has your money they are reluctant to part with it even if they are in the wrong. Does the interest they earned on the money deducted get paid back when you are finally refunded? I guess not. To me MTN is sitting high on the list of dishonourable companies to deal with. Their clients made them the company they are but they have zero regard for those clients. Very sad.