Nitty-Gritty of Contract Upgrades

I have been a loyal MTN subscriber for 10 years and have upgraded my mobile contract in March 2015 and it moved from an R value based contract to a min. based contract. This was on recommendation by a Service Agent at the Umhlanga MTN Service Centre. I was ensured that my R value balance of R1858 will be transferred to my new account, which happened. <br> In Early Oct I tried to use this R value to purchase additional airtime and data and the balance disappeared from my account. On querying it with MTN I was told that it had an expiry date of 6 month on it. I was told that this was apparently in the fine print of the Terms and conditions. <br> I appreciate the implications of the policy and my unhappiness is the following:<br> - The Rand value balance was transferred over 4 previous contract upgrades without any issues<br> - The change was made on the recommendation of a Service agent who neglected to notify me of the expiry<br> - MTN taking a month to deal with a customer query and then quoting me the same policy<br> - Based on the above feedback, that my request to get this value reinstated for usage was not even considered .<br> My experience is 'Quick to Sell - Slow to service' Time to move?????