MTN false advertising

I recently went to MTN , Liberty Midlands mall, in Pietermaritzburg. I signed up for an upgrade for a Samsung A36 with a free R1000 voucher with ear pods. However, after I processed the upgrade, I was advsied that the R1000 voucher was no longer available. I was very disappointed as I am a loyal MTN customer for many years. I called the Branch and MTN and they were unable to asssit. I beleive that MTN are misleading the public with false advsertising. If I was informed at the time of signing the contract that the voucher was no longer available, I would have have made other arrangements.At the bottom of the advwert in very small writing it was mentioned that the voucher was for eligiblethe first 1000 customers.Very disappointing. I have been mislead by MTN.