I think it is about time to start a campaign to kill off 0845 and 0870 numbers, and where better to do this is Tesco Stores.
If everyone who shops at this shop group, was to query the phone number on their receipt, at the customer services desk, or keep ringing their freephone (0800 50 55 55) number and requesting the correct number, I'm sure they will give in, in the end.
I have used the tale of "Those 0845 type numbers are barred on my line" and it does seem to work. Then once the number has been found, of course enter it on this site.
If we all got together on a campaign like this, then once it really started to take effect, the progress will speed up once the word gets around and the newspapers have a headline such as "Major Supermarket Group beaten on a phone call price scam"
If a campaign was to take effect during November and December, even making a repeat call after getting another receipt, then I'm sure it would get some results in the mad rush up to Christmas