I am new fido customer they promise me 10$ discount on my account and after that on the same plan I got good deal and I activated that plan accidently now they are saying on this plan you can not get 10$ discount and it will charge me a lot more than I was going to pay and now I want to go back to my old plan can you plz change it back?
Welcome to the community!
Usually, when changing your plans all discounts are removed also. Since you got a promotion with the credits and it has been removed it might not be possible to revert back to it and if the promotion is not available anymore it makes it even harder.
Your best option would be to reach out to customer service and they can go over your account and best advise you if it is possible.