Gareth Fuller / PA Images

If you were one of the 1.9 million people who were locked out of their TSB bank account for more than a week due to a catastrophically bungled IT system migration, you can now claim for some compensation.

To make a claim for compensation, visit the TSB complaints website. You will need to provide a few details, such as your bank account or credit card number, and how the system failure affected you.

If you explain to TSB that you lost some money because of the outage, you should get everything back. If you didn’t lose any money, you can still complain, but you might not get anything. Early reports suggest that TSB is giving some customers an inconvenience fee of between £25 and £50. TSB says that it will “make sure that no customer is left out of pocket.”

If you’re concerned about any overdraft fees or interest charges that were levied during the outage, then there’s no need to complain to get a refund: TSB has waived all such charges for March and April. This applies to both business and personal account holders. As an added bonus, TSB has upped the interest rate on the Current Plus current account from 3% to 5% on balances up to £1,500.

If the system outage caused ongoing financial distress or debt difficulties, TSB recommends that you phone up their telephone banking service or visit a branch.

What caused the TSB banking system outage?

TSB began migrating 1.3 billion records from an old IT system on the evening of Friday, April 20. The migration should’ve finished on Sunday evening – but instead, the new system was riddled with bugs and was inaccessible for many customers. In some cases, customers saw account details and balances that didn’t belong to them. TSB’s chief Paul Pester said that “402 customers could see some data that we would normally not show them.”

TSB had previously been a part of the Lloyds TSB banking group, but it was acquired by Spanish banking group Banco Sabadell in July 2015. TSB continued to use Lloyds’ systems while Sabadell developed a new platform in the background. The switchover to that new platform on April 20 is what caused all the problems.

Now read: How to switch bank accounts