I called them to get...

I called them to get one of my contract canceled, and told them R900 is rather too heavy for me, then the lady said she will change my package to be less on 2 contracts, yes it was changed however receiving the invoice I'll be paying twice the amount and they're telling me it's migration fee, why she never mention the R900 migration fee to me, if I was unable to pay R900 where will I get R1800 from