Throwing customers money away

I've been a MTN subscriber since 2004. Today I wanted to migrate my contract to prepaid. I have more than a gig of data which I purchased (not part of my contract). The consultant told me over the phone that I have 2 choices:1) migrate today and lose my data or 2)use all my data and once it's done, then call in to migrate to prepaid. I told him that my contract does not allow me to buy airtime and I do not want to continue running a bill. So basically, in order for me to not lose the money I spent on data I have to continue running up my bill. He acknowledged that after the migration I would like the data I paid for and will lose be reloaded. He made it clear that that would not happen and because if MTN does it for me, they have to do it for everyone. So in essence, MTN is *****ing from 1000s of people. How do you justify taking a consumers money and just saying, 'tough, you're going to lose it'? I have been a long time and loyal consumer of MTN. It is clear to me that this is not a service provider that values it's consumers and has no qualms with ripping us off. Because of this, instead of migrating to prepaid, I'm migrating to another service provider.