Breach of contract

On 19 Jan 2018 I took out a contract with MTN for the 8gb (4gb anytime and 4gb night-time) sim only data promo and received notification that it was activated and my cell number - ********** 865. However, I only received 2gb of data for the month and not the 4gb as promised. On 23 Jan, I went into the service centre at the Garden Route mall, the lady was very helpful and logged the problem for me. I received a message via sms that this had been logged and was given a ref. Number: 1- ********** 7924. Then on 26 Jan I received another sms telling me that this had been resolved, despite the fact that it had not been resolved and I had still not received the missing data now for the second month. Mtn did not hesitate to bill me, however! I rep**** to that sms to that effect, but received no reply. I have since sent a mail on their contact page but so far, they have not even bothered to reply. I just want to add that the staff at the service centre have been very helpful. The problem lies with MTN itself, and although I have paid each month for my contract, MTN has been in breach of the contract themselves. I have been using MTN for years and find this lack of loyalty to their customers shocking.