And there is a bit of an error with the prestige system as I discovered playing the game again as the save game doesn't seem to save.
When you prestige, the number of new loyal customers is VISUALLY affected by the bonus, but in reality the number you see needs to be divided by your multiplier to calculate how many new customers you actually have.
For example I have 270 customers with a x28 bonus. I have have 7023 new customers with a x24 bonus. 7023/28=250 which is the actual number of new customers and explains why the new bonus is lower than the current one.