Five “predatory” firms who targeted elderly and vulnerable people with more than 750,000 marketing calls have been fined £405,000.

The companies targeted people signed up with the Telephone Preference Service (TPS) – a register for those who do not want to receive marketing calls – to sell insurance for appliances such as televisions, washing machines and fridges.

Most of the companies deliberately targeted older people after buying details about their age and landline numbers from third parties, the Information Commissioner’s Office (ICO) said.

Many of the complainants said the people who were targeted were vulnerable, with some suffering with dementia or other underlying health conditions.

One elderly individual had their savings whittled down from £8,000 to £500 in just over a month, while another elderly person with short term memory loss was being charged £500 a month for insurance they mostly did not need.

The ICO investigated the firms – Domestic Support Ltd, Home Sure Solutions Ltd, Seaview Brokers Ltd, UK Appliance Cover Ltd and UK Platinum Home Care Services Ltd – after receiving complaints from the public and information from Action Fraud, Trading Standards, Which? and the call blocker provider trueCall.

Information Commissioner John Edwards said: “These are unlawful predatory marketing calls that were targeted at some of the most vulnerable members of our society and driven purely by financial gain.

“It is clear from the complaints we received that people felt frightened and distressed by the aggressive tactics of these companies, sometimes giving their financial details just so they could hang up the phone. This is unacceptable and clearly exploitative.

“It is only right that we take tough and prompt action to punish those companies responsible using our full powers.

“Companies making similar nuisance calls and causing harm to people can expect a strong response from my office. I encourage anyone who is being pestered by other rogue operators, or knows a family member or friend who is, to report them to the ICO and we will step in to protect the public from these invasive calls.”

The ICO said it was continuing to investigate a number of other companies that appeared to be operating in the same way.

Age UK director Caroline Abrahams said: “This is very welcome action from the ICO. Targeting vulnerable older people with predatory marketing calls is unacceptable and must not be allowed to happen.

“Feeling in control of incoming calls and safe at home is incredibly important and we would urge older people to sign up to the Telephone Preference Service or install a call blocking device.”