If your new provider is using the same Openreach connection into your home as BT , then the new company ( whoever it is ) should have explained to you ‘not’ to contact BT yourself but to leave it to them to serve notice on your behalf to BT. By calling BT yourself and effectively saying ‘cancel my service’ , BT have done what you wanted , albeit, it’s been done earlier than the date that was mentioned, they don’t interrogate you about the reason for your call , and if it’s appropriate, ignore your request.
If you hadn’t called BT , the migration would have taken place on the date the new provider gave you , and your BT service would have remained in place until that date.
As far as charges , if you are asking BT to temporarily restore service until the date this new company gave you , you probably will have ‘hassle’ with charges , as it will appear that you are leaving the newly set up BT contract early ( even if you argue it’s not really a new contract but simply the way to get BT service restored) and no doubt you will be ( initially at least ) charged for the early termination of this ‘new’ contract, you may think it’s BT simply restoring service , but it will appear as a new contract with a minimum term, so this is really just a heads up on that probable future aggrevation.
If you were unaware of the correct process that’s really a failure of the new provider , not BT , and you probably would be better served by asking the new provider to expedite their provide order, rather than getting BT to restore service, but that ship has probably already sailed.
