"HEARTLESS" thieves stole lead from the roof of The Children's Trust's Tadworth centre during two early morning raids.
Water then seeped into rooms wrecking fundraising equipment and donated goods.
Though volunteers worked hard to recover as many items as possible, some were damaged beyond repair.
Subsequent renovation and security installations have cost the trust hundreds of pounds.
Children's Trust chief executive Andrew Ross said: "It's hard to believe that people would take an opportunity to steal from a children's charity.
"It's a heartless and sad act that has shocked and disappointed us all at The Children's Trust.
"Unfortunately, it has taken a lot of money and time to repair the roof, but we have taken measures to increase security and installed additional CCTV equipment."
Police are appealing for witnesses following the two thefts, which were at about 4am on October 17 and between 1am and 5am on October 20.
During both raids, the thieves took lead from the roof of the charity's stables.
During the second incident, they damaged other areas of the roof and a golf buggy, which staff use to move around the 24-acre site.
The damage to equipment, some of which had been donated for sale in the trust's charity shops, caused an outcry from staff.
Angie Turner, head of corporate partnerships at the trust, said: "Our fundraisers and shop managers work so hard to raise money.
"It's so frustrating then that people can carry out a malicious act like this.
"However the team pulled together to ensure we could save most of the fundraising materials and shop stock."
Call police on 101 with information, quoting references RB/12/8498 or RB/12/8619.
