R2 300 for terminating my contract a week early!!

When MTN notified me that I was due for an upgrade in July, I assumed that this meant that my contract had come to an end. After being a loyal customer to MTN for 20 years, MTN was unable to match a contract that Vodacom was offering. I kept trying for 3 months and eventually I had no choice but to port to Vodacom at the end of October. Not once did customer retentions try to keep my business - nor did they EVER mention anything about an early cancellation fee. I ported to Vodacom in October and suddenly now in December I was billed R2 307!!! Not once was I told that my contract was only up a week later (8 Nov) and that there would be a 'penalty for early cancellation'. I have been begging MTN to please reverse the fee that I did not agree to and was never told about but they are simply not interested! Apparently I should have read the T's and C's in my contract - that I signed 20 years ago!