The following advice comes from an insider whom I am keeping anonymous for the obvious reason that his suggestion isn't strictly above board. But since it is only a means of clawing back what is rightly owed, then one might say that the end deserves the means.

My caller has been monitoring his telephone charges to Smiths News and has been finding that he is having to pay for the company's mistakes. "Each call costs about 25p-30p. If supplies are incorrect I ring up and can ask for a telephone credit and I might get 10p at their discretion. So I've decided I'm not giving them back any 'overpacks'. I was with Dawson for nine or 10 years and I never did this. But I had four extra papers today and I'm going to keep them."

His phone bill itemises only the calls that cost more than 20p so he cannot accurately work out how much he isn't getting compensated for.

He has another tip regarding vouchers. After experiencing similar problems to other newsagents with getting his money back, he sends them back special delivery. "It can cost over £7 to send off, so I started charging customers 50p a week or 8p a day for a voucher to cover the cost."