Image copyright Thinkstock Image caption Some charities outsource telephone fund-raising to call centre companies

Charities could be alienating their supporters and causing damage to their brands by using aggressive techniques to raise money, according to one of the sector's leading think tanks.

NFP Synergy has warned charities they must stop bombarding their supporters with phone calls - or risk losing them.

Conservative MP Charlie Elphicke says cold-calling is toxic for a charity's reputation.

But charities insist telephone fund-raising is vital.

The most recent figures, from 2011-12, show charities made 11.5 million fund-raising phone calls in the UK, up from 10 million the year before. That year complaints rose by 64% year on year to nearly 6,400.

'Hounded'

The results of a new survey by NFP Synergy, a research company which counts some of the country's biggest charities among its clients, found that more than half of people are "very annoyed" by telephone fund-raising (51%) and doorstep fund-raising (54%).

Image copyright Other If someone just hung up on us or was angry or upset, we were told to keep calling them back Andy Lloyd-Williams, Former call centre company employee

Claire McGowan, 32, a writer from south-east London, began to receive calls from a charity she supported after she cancelled her direct debit following a marriage break-up.

"They called me every day, day and night, for three weeks, even after I'd asked them not to. It was a salesman trying to get me to sign up again, playing a guilt trip and I felt hounded in my own home," she said.

"I would have gone back to them one day but it's put me off. I'll be much more selective if I give to charity in future."

Andy Lloyd-Williams, 24, from Southampton, worked for a call centre company hired by charities to raise funds by calling potential donors and convincing them to sign up to direct debit agreements.

"I had to phone people, give them a sob story, make them feel guilty and get their money," he said.

"The company rule was that we had to hear them clearly say no three times before we should stop. If someone just hung up on us or was angry or upset, we were told to keep calling them back."

'Pushy' fund-raising

MP Charlie Elphicke, who last year ran a campaign calling for a crackdown on street "chuggers"- street charity fund-raisers - says vulnerable people are being targeted.

"You've got people who are not necessarily committed to the charity just calling up on commission, so they're paid by the amount that they raise. It's not policed properly by the charity because they've outsourced it.

"Charities are damaging themselves in raising money in this way. They just put people off the idea of charitable giving and they make the charity name and the charity brand more toxic," Mr Elphicke said.

Joe Saxton, director of NFP Synergy, said there was no evidence yet that cold calling had affected fund-raising capabilities but that "the real danger is that individual charities lose out or you see people giving up on this kind of fund-raising and that's why charities have a real dilemma.

"What we need to see is more self-regulation by charities. Street fund-raising, which a lot of people have found very annoying in the past, has a much better reputation today than it did five years ago and we now need to work as a fund-raising industry on the doorstep and telephone fundraising as much as we've worked on street fund-raising."

The Institute of Fundraising, which set guidelines for charities phoning the public, said: "Fund-raisers know that it is absolutely critical to maintain public trust and confidence in charities, and a fundamental part of this is to fund-raise in the right way.

"Any complaint is regrettable and is treated seriously by our members, but it is important to keep this in proportion and remember that the overall number of complaints is very low compared to the number of times people are asked for support."

The Fundraising Standards Board, which regulates charity fund-raising against the Institute of Fundraising's code of practice, said it is "working with charities to identify the main causes for complaint and whether this increase has continued into 2013.

"Any allegation of 'pushy' fund-raising would be of great concern to us at the FRSB, with the potential to damage public trust and confidence. Charities must listen carefully to any such feedback from their supporters and consider how this might influence or improve future campaigns."