Inertia selling
This are illegal under UK laws dealing with unsolicited goods and so the domain names may ''be treated as an unconditional gift''.
So: if you get a bill, tell 123-reg/names-co that you do not want it, that you will not pay it and that any attempt to collect money via direct debit will be fraud. It they take money: demand that the bank return it. For good measure you could tell the scammy registrar that if you need to recover the money that you will charge £100/hour for your time, with a minimum of 1 hour.
They tried the scam to make money so hit them where it hurts by extracting even more money from them.
Since it is fraud: why not also report it to the police.
Biting the hand that feeds IT
