No one needs a 647 number. 416 and 437 work the same way.
I live in what was known as 519 (Southwestern Ontario) for years, always have a 519. It's a large area. Now the area code geographic area is also 226 and 548.
Do I want to change from my current 226? No, I've had it for 15 years.
With province-wide calling, unless you're in a Provincial border town, it makes no difference what your area code is, as you can call anywhere in your province. A Canada-Wide calling plan has no restrictions. Local calls do not exist at Public Mobile
Unfortunately, this has happened before. For some reaosn, the system has a habbit of sometimes (but rarely) assigning a phone number to a new customer that is already active and being used by someone else. The only solution is to change your phone number (which you will be required to do regardless). If it is a new number that you took, i would not even bother waiting for moderators, and I would just log into your self-serve account and change it from there.