Online fundraising portal JustGiving says it has fixed problems that prevented many users from making donations through the website after it was re-launched in June. Technical issues meant 20% of donations were not processed between 20th and 27th June.

Error rates are now down to 3%, in line with the norm the website sees as a result of details being entered incorrectly or being rejected, JustGiving has confirmed to Philanthropy UK.

Zarine Kharas, chief executive of JustGiving, blamed the situation on the fact the company had not tested the new website extensively enough. Charities that had used the site from 20th-27th June have been offered a refund of the 5% transaction fee.

A huge number of complaints were made on the JustGiving blog following the problems, and Kharas apologised to all users.

“We take full responsibility for our mistakes and we are truly sorry for the frustrations everyone has been experiencing,” said Kharas, on the JustGiving blog. “It probably doesn’t feel like it right now, but we’re confident that this new site will, once it’s running smoothly, deliver a better service and much faster service to people donating.”

The changes to the site were needed “to support the continued growth in donations": there were 52% more donations on Sunday 19th July compared with the same Sunday in the previous year.

Outstanding issues have reportedly been resolved, but anyone experiencing problems should call the helpdesk on 0845 021 2110 or email help@justgiving.com. Justgivng aims to respond to all requests within 48 hours.