If you called 03451 720088, of course they need to check that you are who you say you are, @Henry13.
The usual method for authentication these days, it seems, is to send numbers to people's phones.
They would also check details, like your billing address.
The only way you could have been scammed is if people phoned you, pretending to be Talktalk.
If it was the other way around and you phoned the above number, go with their security checks.
They are simply ensuring that you have the correct ID, and are not some imposter making mischief with your account / service.
Gliwmaeden2, a fellow customer.
