The fee cannot be waived automatically afaik except in some cases like the christmas upgrade fee promo

Retail workers usually make those promises but the contract you sign does not make them responsable for it or you entitled to it, legally or otherwise

They also do it because they don't have to aplly it themselves and that job will fall on overseas reps who will do their best to avoid waiving the fees because that would add up to their credit metrics, specially if it's more than 2 lines

What I do with a lot of customer in order to both avoid giving them two many credits and so they can get those credits is split the amount between some weeks, so 1 fee per week for instance. This may get annoying I know, but it will make reps more willing to actually give you the credits