thescullster wrote

Came to renew the car tax last week and the credit card is near limit.

Don't like using debit card on-line due to (perceived) lack of protection
against fraud etc.

That's a myth. Mine has exactly the same protection
against fraud as the credit cards have.

So decided to use debit card

In your case what you should have done is move
some money from the debit card to the credit card
and do the car tax on the credit card as usual.

and touch tone automated phone renewal.

Although this takes much careful input of numbers into phone, it all went
smoothly.

Got to wondering whether there are security loopholes using this method.

Much worse than doing it electronically in fact.

Clearly with on-line card detail entry there is possibility of key log
virus,

Trivially eliminated by doing multiple anti virus
with a number of different free antiviruses first.

scam sites,

Trivial to avoid those with the car tax.

wireless sniffing (if you use wireless for financial transactions - I
don't).

Trivial to avoid by using a secure wireless connection.

But are there equivalent weaknesses in these automated phone transaction
systems?

FAR worse in fact. Anyone can tap your phone
line and trivially record your card details that way.

Also, does anyone know if a written acknowledgement is sent as proof of
tax status?