OLD NUMBER vs NEW NUMBER *******!!!

I have been a loyal MTN Customer for the past 20 years. I have recently discovered that new phone that i have (with the MTN Number), the price plans are not the same. For an example, the 30 days 1GB Data Bundle on my recent number is R99 and 30 days 1GB Data Bundle on my old MTN number is R149. Same applies on the Social Bundles i.e. 30 days 1GB Whatsapp Bundle is R30 on my recent MTN number and 20 days 1GB Whatsapp Bundle is R30 on my old MTN number. Shouldnt price plans be the same? I'm so dissapointed with the response i got from the Customer Service agent who told me that the price plans are for recent MTN customers, How is that even possible. I'm utterly disgusted and tired of MTN ripping me off while i stayed so loyal to them over the years.