Pensioners have spoken of their frustration at being told that their once-free Zumba classes will now cost more than £300 a year.

Over-60s attending the fitness sessions on Monday evenings at Becontree Heath Leisure Centre, in Althorne Way, have been informed they must now pay £7 for the classes due to a recently discovered error.

They had previously been able to take part in unlimited free classes by signing up to the Ageing Well scheme for £1 a week but must now pay standard prices for sessions after 5.30pm.

Kathleen White, 69, of Grey Avenue, Dagenham, said: “The new charge is exorbitant – none of us can afford it.

“I have a heart problem, so I need these classes – my cardiologist even told me he’d seen a huge improvement recently and said, ‘whatever it is you’re doing, keep doing it.’ But how can I if it costs too much?”

Kathleen said she and the other over-60s spoke with the management and offered to pay £2 for each session but are yet to hear back.

The dance group did attract more than 30 people, half of whom are under 60 – and the younger members are standing by their elders.

Tracey Jacob, 48, of Lodge Avenue, Dagenham, said: “Without them, the atmosphere isn’t the same – we built up a social group. It is so unfair.”

A spokesperson for the council said: “Unfortunately – or very fortunately for the people who were able to benefit – the centres’ ticketing systems were mistakenly allowing members of the Ageing Well scheme access.”

She said over-60s could still attend the sessions, but must pay the £7 fee because of capacity concerns.

But Kathleen said: “The silliest thing is without us the class is down to 13 or 14, and we were told if the numbers drop below 12 it will close.

“We’re willing to pay, but £7 is extreme – I went to the Pineapple Dance Studios in Covent Garden for Zumba as a treat, and it was only £5.50!”

Kathleen Summerscales, 67, of Joyners Close, Dagenham, said she is not willing to let the issue slide.

“If they think this is over, they’re wrong,” she said. “We’ll go as far as David Cameron if we have to. They have drawn us in and now they introduce this charge – it is their mistake, and they should swallow it.”