Did you apply a referral code to the second account you set up? If so, then the account that received the referral bonus would get more than the second account.
That’s a good analogy, but PM followed the contract terms with you and provided more than the requisite notice, so no severance or other compensation is required.
Your actual subscription has not likely increased, but the cash discounts you previously received have been replaced by the Public Mobile points program effective this month.