Buttermarket Shopping Centre has apologised to customers of its car park who have been charged above the £2 flat rate for parking after 7pm.
Customers parking in the car park in Ipswich town centre have been charged £4 rather than the £2 if they park after 7pm.
A statement from Buttermarket Ipswich said the centre had apologied to customers for the inconvenience.
The statement read: "We are aware of an intermittent issue and are working hard to resolve it.
"We apologise to customers impacted by this problem and are happy for them to contact us here in order for us to process a refund.
"In the meantime, until the issue is resolved, we are removing the evening tariff for all customers."
It is believed the issue relates to the time being an hour out on the system, since the clocks changed to British Summer Time on March 26.
The car park, which is open 24 hours a day seven days a week, has space for up to 370 cars and is located below the Ipswich shopping and dining centre.
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