Door-to-door gas company reps have received a broadside after persuading a 90-year-old deaf woman to sign on the dotted line.

A canvasser called at her home in the Low Moor area of Bradford and persuaded her to change her gas supply from British Gas to Scottish Power.

But he failed to tell the pensioner, who does not want to be identified, that the British Gas payment stamps she used could not be transferred to the new supplier.

The gas industry watchdog says people should be fully aware of what they are doing before they sign on the dotted line and changed from one supplier to another.

And Scottish Power says it will investigate the case.

The pensioner's anxious niece told Rights and Wrongs: "What worries me is that my aunt paid her gas with British Gas stamps and she was not told they would be worthless with Scottish Power.

"She has always paid with stamps - she prefers it - and she had about £100 worth. There must be a lot of people who have signed up and don't realise they won't be able to use the stamps if they change."

She said she had since written to Scottish Power cancelling her aunt's application.

"She was under the impression she had to sign because it was something that was going to happen anyway in the future," she said.

Hilary Putman, regional manager of the Gas Consumers' Council, said the watchdog had received a number of complaints since gas supplies were deregulated in Bradford at the end of March.

"Our advice is to read the document carefully - read the small print and be aware of exactly what you are signing for," she said. "It is the gas supplier who is responsible for canvassing agents and there are some agents who are desperate to get the business and are not playing the game according to the rules."

She said householders could use British Gas stamps to pay their final bill if they transferred to another company and get a refund on any they had left.

West Yorkshire Trading Standards divisional manager Paul Cooper said: "The whole issue of gas deregulation is something we were concerned about before it took place and we are concerned about now. "The method employed to contract new business is inevitably door-to-door canvassing and you are relying entirely on the integrity of the people the gas companies employ.

"Some actually employ sales staff themselves so there is a greater degree of control. But some of the people out there trying to persuade people to change their gas company are self-employed, often working on a commission-only basis.

"There is an incentive for them to go a little further and not take no for an answer."

But Mr Cooper said people have 14 days to reconsider their decision - and only have to give 28 days notice later if they want to part company with that supplier.

A Scottish Power spokesman said the sales visits in Yorkshire were being carried out by a canvassing company.

"We will be taking this complaint up with the company - we are fairly keen to make sure it doesn't happen again.

"We do have strict guidelines for our sales force when canvassers visit elderly people.

"It is left to the individual's judgement whether an elderly person who runs a household should be asked to sign up for Scottish Power gas.

"If they live on their own in sheltered accommodation, the rule we insist on is that everything should go through the warden.

"If this lady paid for her gas with stamps, she should not have been signed up because with this sort of customer we have a telephone advisory service we ask them to call.

"The canvassers should only sign up direct debit or quarterly credit customers."

The spokesman said the canvassing company employees usually received no basic pay and a large commission for results or some basic pay and a smaller commission.

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